Every human institution needs a backbone that will effectively take care of all its operations. Since a school is a human institution that is inclined in facilitating the quality of educational service, promoting knowledge and enhancing the skills and ability of the students, teachers and administrators, effective managers are needed to live upto the tremendous task of educating the future generations. Each educational institution is unique, just as an individual is to another. This uniqueness paves the way to the development of different personalities. As unique administrators, they employ different styles of exhibiting their leadership in their institutions. A quality educational institutional or a school can also be manifested not only in the administrators, but also in the performance of the teachers and students. If the teachers and administrators performed their duties and responsibilities well, it can be deemed to be an excellent school. If the leadership of the administrators is good, the performance of the teachers and students would become better. During this 21^st century, leadership skills are needed to fit the modern day learning environment. Educational leaders are more concerned about instructional requirements and the expertise of the teachers on how they will be able to share their knowledge to their students. Improving every aspect of skills in the point of communication, innovative, creative, problem solving and able to have a good relationship may help to become a better educator or an administrator. However, time is running out so teachers and administrators should adapt to the situation and understand it. In order to be able to fit to this modern learning environment, the school administrators should possess the 21^st century leadership skills needed for them to be effective in their roles as an educational leader.

Education evolves through time and as it evolves, education should be up to date. The people who are in the field in education should make sure that they will give the students quality education that is needed in time. However, in order to do these things, skills are needed. According to the Leadership Skills (MTD, 2010), these skills should be considered as tools in the toolbox – the toolbox of a leader who can be flexible to the needs of his or her team – but also to the situation itself. Leadership skills are tools needed to work with people to help them improve their abilities to cope with the increasingly complex and fast changing world (Gordon, 2018). Principals are leaders so they need these skills to lead a school. Piaw et al. (2014) said that leadership skill of school principals is often the key factor of difference between effective and ineffective schools. These schools provide education to the future builders of a nation. Doumbia (2013) said that education is the most important element in the evolution of the nation, a nation that is built by knowledge and leadership. According to Diaw et al. (2013), school principals with good leadership skill encourage positive school climates, including highquality of school culture; teaching and learning; assessment; academic and non-academic performance; two-way communication; accountability; teacher and student attitudes; and relationship among school, families and the broader community. Hence, the researcher aims to discover the different 21^st century leadership skills and skills quotient possessed by the principals of different secondary schools in Nakhorn, Nayok by self-assessment and assessment by their own teachers so as to find out if they fit to the modern day learning environment.

1.1 Leadership

According to Katz (1974), skills approach to leadership suggested that leadership or effective administration is based on three skills: technical, human, and conceptual. Technical skill is proficiency, based on specific knowledge, in a particular area of work. To have technical skills means that a person is competent and knowledgeable with respect to the activities specific to an organization, the organization's rules and standard operating procedures, and the organization's products and services. Human skills are proficiency in working with people based on a person's knowledge about people and how they behave, how they operate in groups, how to communicate effectively with them, and their motives, attitudes, and feelings. Conceptual skills allow you to think through and work with ideas. Leaders with higher levels of conceptual skills are good at thinking through the ideas that form an organization and its vision for the future, expressing these ideas in verbal and written forms, and understanding and expressing the economic principles underlying their organization's effectiveness.

1.2 Leadership Skills and Practice

Leadership is a set of skills that can be learnt. Burkus (2010) stated that skills theorists sought to discover the skills and abilities made leaders effective. Similar to trait theory, skills theories are leader-centric, and focused on what characteristics about leaders make them effective. Mumford et al. (2000) said that the skills approach implies that many people have leadership potential, and if they can learn from their experiences, they can become more effective leaders. Competencies are the most important element in this model. Competencies lead to leadership outcomes, but themselves are affected by a leader's individual attributes. In addition, the impact of leaders' attributes on leaders' competencies and leaders' competencies on outcomes is dependent on career experiences and environmental influences. According to Amanchukwu et al. (2015), the skills theory states that learned knowledge and acquired skills/abilities are significant factors in the practice of effective leadership. Skills theory by no means refuses to acknowledge the connection between inherited traits and the capacity to lead effectively, but argues that learned skills, a developed style, and acquired knowledge, are the real keys to leadership performance. A strong belief in skills theory often demands that considerable effort and resources be devoted to leadership training and development.

1.3 21st Century Leadership Skills

Educational leadership skills comprise of setting instructional direction, teamwork, and sensitivity. Setting instructional direction is an ability to implement strategies in improving the education from the view of the teacher and student, the teaching and the learning. Developing towards the way of the mission and vision in order to get a clearer goal is to provide guidance and encouragement. Teamwork is working together for the same goal by means of encouraging and motivating the members to work as one. Individuals also have a sense of belonging to the group, and the range of views and diversity can energize the process, helping address creative blocks and stalemates. Sensitivity is a skill that needs an emotion attachment. In this term, knowing what to do in a situation or an event that the person may know how to deal with it. The problems are concerned with sensitivity training as a means for understanding and assisting in the resolution of interpersonal and group developmental dimensions of the problems (Wang, 2012; McLean, 2016; Marshall, 1970).

The resolving complex problems is comprised of the concept of judgment, results orientation, and organizational ability. Judgment is an act based on empirical and logical decisions that are made by facts that they have. It is also knowing what is important and what is not in making decisions that is relevant to the situation. Results orientation is knowing and recognizing the end game of any situation and also taking responsibility of the action taken. Strong capability in focusing on tasks and results help the leader and the team accomplish tactical work, such as achieving goals, solving analytical problems, project planning creating innovations, maintaining productivity, and making fast decisions. Organizational ability is a skill that is important in making plans of works so that required materials can be used properly. In other words, it is management of time and work. It is also about knowing what you want, and then prioritizing your activities and planning your time around activities that will help you achieve those goals. (Harrisson, 2018; Rykrsmith, 2014; Sperling, 2017).

Communication has two aspects oral and written communication. Oral communication is a process of expressing one's idea through speaking. In connection with this, verbal words are used in communicating in a small or larger group as a result of direct interaction with a person. While, the written communication involves characters that expresses the ideas through writing. Communication is not simply through words, but also through actions taken in your work. Every communication, oral or written, builds a picture and creates an impression about you and your leadership (Chand, 2018; Miller, 2019).

Developing self and others has also two aspects such as developing others and understanding own weaknesses and strength. Developing others is a very difficult job to do in the sense that it depends on the person whether they wanted to develop themselves or not and guiding the members of the group through positive and negative reinforcement. Understanding own weaknesses and strength is not easy to see if the person is being ignorant. Weaknesses are the things that hinders us to step outside the boundary. Using our weaknesses to motivate to work harder and to aim beyond the borders of impossibility.

2.1 Research Questions

This study aimed to identify the 21^st century leadership skills quotient of the principals based on self-assessment and their department head's assessment. Figure 1 shows the conceptual framework of the work Specifically, it sought answers to the following questions:

• What is the 21^st century leadership skills quotient of the principals based on self-assessment and observer assessment?
• Is there a difference between the self and observer st assessment of the 21^st century leadership skills quotient of the principals in Nakhorn Nayok?
• Is there a correlation between the self-assessment and st observer assessment of the 21^st century leadership skills quotient of the principals?
• Are there skills that need to be improved to meet the st demands of the 21^st century leadership skills of the principals?
• What method will be used to develop 21^st century skills?

Figure 1. The Conceptual Framework

This study used quantitative method of research wherein the responses were gathered, tabulated, and analyzed. Mean data were used and statistically analyzed using Pearson r to find out the correlation and t-test for independent events of the self assessment and department head's assessment. A questionnaire was adopted from the National Association of Secondary School Principals (2010) in the United States of America to find out the 21^st century skills quotient of the secondary school principals of Nakhorn Nayok based on selfassessment and department head's assessment. Ethics in research was taken into consideration by asking permission from the schools where the study was conducted. Even if the instrument was adopted, it has to be translated to the Thai language and has undergone thorough face validity and reviewed by three (3) experts in the field of education. The pilot of the questionnaire was done among department heads in another school and the reliability test of 0.965 was computed using Chronbach alpha. This study gathered data from the principals and their department head in the Academic Year 2018-2019 in the province of Nakhorn Nayok, Thailand. This study included the school principals and their department heads in this area. In this technique, all principals and eight (8) department heads per school were selected except for Suwanprasit school with six (6) department heads and there were ten (10) schools involved in the study.

The study focused and is limited on self-assessment and st department head's assessment to identify the 21^st century skills quotient of the principals secondary schools of Nakhorn Nayok Province. However, during the retrieval of the questionnaires, some questionnaires were not answered completely so the researcher decided to discard those with incomplete answers. Only seventy six (76) department heads and 9 principals answered the questionnaires which served as the sample of the study. The results of the study will only be conclusive to the province where the study was done.

5.1 Results

The leadership skills in this study were measured according to their indicators, which includes setting instructional direction, teamwork, sensitivity, judgment, result orientation organizational ability, oral communication, written communication, development of others, and understanding own weakness and strength. The self-assessment and department head's assessment were compared and analyzed. In addition, the self-assessment and assessment of their department heads were correlated.

Table 1. showed that the perception of the 21^st century leadership skills of the secondary principals in terms of setting instructional direction has an over all mean in selfevaluation of 4.53 and in the department heads evaluation of 4.45. In all of the indicators, the mean ranges from 4.33 to 4.89 (self-evaluation) and 4.07 to 4.67 (department heads evaluation). This is an evidence that some how the secondary schools principals frequently to almost always practicing the setting instructional direction. The data also revealed that the principals rated themselves highest in the skill on generating the enthusiasm and persuading others to work together to accomplish common goal for the success of every student

Table 1. Difference of Self-Evaluation and Department Head's Evaluation on Setting Instructional Direction

However, they rated themselves lowest in skill on encouraging innovation to improve teaching and successful learning for every student, developing alliances and resources outside the school to improve the quality of teaching and learning and clearly articulating expectations regarding the performance of others as it relates to effective instruction and student success. While the department head evaluated the principals highest in the capability to acknowledge and celebrate the achievements and accomplishments of others in their efforts to ensure student success. In contrast, the department heads rated their principals least on their capability to encourage innovation to improve teaching and successful learning for every student.

Furthermore, the t-test reveals that there is no significant difference between the self-evaluation and head teacher evaluation. According to Hallinger ( 2011), the concept of instructional leadership is still in line with the needs and requirement of policy, research and management and practice of school leadership. In connection with this, the assessment of the extent of instructional leadership practice in every school should be identified as effort to produce high impact leaders. The principals of Nakhorn Nayok schools assessed themselves high and similarly, their department heads rated them high in their setting instructional direction thus these leaders fit to this 21^st century skill. Furthermore, Hallinger (2011) believes that policy makers and policy practitioners believe that instructional leadership is a key factor in making effective schools.

Muda et al. (2017) concluded that instructional leadership and improved quality of education in the 21^st century had been proven to have a strong link therefore the role of instructional leadership in improving the quality of education should not be ignored. Furthermore, it was discussed that instructional leadership is still relevant to be practiced to manage education changes in the 21^st century. Therefore, the school leaders who act as instructional leaders need to strive to be a high-impact leader to lead the implementation of education changes effectively. This conclusion, therefore strengthens the finding that the principals in Nakorn Nayok Schools are 21^st century leaders because they can set instructional directions.

In addition, Rahman et al. (2019) strengthens the idea that instructional leadership practices related to clarity of explaining the mission and vision of the school and encouraging a positive learning climate at school are essential to the improvement of teacher innovation. It was further noted that these predictors are essential to improve the teacher's innovativeness, which is a skill needed in the 21^st century. However, Hallinger (2011) mentioned that the principal has been exhorted to exert instructional leadership, while on the other hand, he has been told flatly that such a role is beyond his or any other human being's capacity. Therefore, principals just should do whatever is possible. On students' achievement, Sim (2011) found out that there is concordance between the level of instructional leadership and the level of students' academic achievement in school. This concordance do exists in both sides of the pole wherein it exists between the high level of instructional leadership and the high level of students academic achievement and also do exists between the low level of instructional leadership and the low level of students academic achievement.

The data in Table 2 showed that the perception of the 21^st century leadership skills of the secondary principals in terms of teamwork has an over-all mean in self-evaluation of 4.60 and in the department heads evaluation of 4.55. In all the indicators of teamwork, the mean ranges from 4.11 to 5.00 in the self-assessment and of the department heads evaluation ranges from 4.47 to 4.65.

Table 2. Difference of Self-Evaluation and Department Head's Evaluation on Teamwork

This reveals that the secondary school principals are frequently to almost always practicing teamwork. The data also revealed that the highest mean of the secondary school principals' self-evaluation are seeking to develop consensus among team members while the lowest mean is seeking input from team members regarding ideas to improve learning. In contrast to this, the highest mean of the department head evaluation is on assisting the team in maintaining the direction needed to complete tasks while the lowest mean is on seeking input from team members regarding ideas to improve learning.

Furthermore, the t-test reveals that there is no significant difference between the self-evaluation and department head's evaluation on teamwork. The principals believe on teamwork as an essential trait in this 21^st century. This finding agrees with Amah et al. (2013) that leadership should encourage the involvement of employees working as a team as this could enhance their responsiveness and commitment to the achievement of the organizational goals. Polega et al. (2019) concluded that teamwork is very important among teachers and principals. Most experts from different professional fields join in teams so as to be more effective in the solving of problems successful in the implementation of projects in organization. This contention supports that principals should also consider that working as a team is essential in this 21^st century even if it is difficult. In support to this, Ariratana et al. (2015) mentioned that teamwork is one of the soft skills to develop among educational administrators.

It is gleaned in Table 3 that perception of the 21^st century leadership skills of the secondary principals in terms of sensitivity has an over-all mean in self-evaluation of 4.47 and in the department heads evaluation of 4.37. In all the indicators, the mean ranges from 4.22 to 4.78 on selfassessment and the department heads evaluation ranges from 4.11 to 4.53 indicating that the secondary principals frequently to almost always practicing sensitivity.

Table 3. Difference of Self-Evaluation and Department Head's Evaluation on Sensitivity

The data also revealed that the principals evaluated themselves highest the skill on interacting appropriately and tactfully with people from different backgrounds and communicating necessary information to the appropriate persons in a timely manner. However, the principals rated themselves lowest in the item of expressing verbal and/or non-verbal recognition of feelings, needs, and concerns of others. In contrast to this, the department heads evaluated their principals highest on the skill in voicing disagreement without creating unnecessary conflict and lowest in the item on expressing verbal and/or non-verbal recognition of feelings, needs, and concerns of others. Both selfassessment and department head's assessment agree in this indicator.

Moreover, the t-test reveals that there is no significant difference between self-evaluation and department head's evaluation on sensitivity. According to Walters (2008), sensibility is the ability to perceive the needs, concerns, and personal problems of others. Moreover, it is also tact in dealing with people from different backgrounds and with this they gain the skill in resolving conflicts. Furthermore, it is also the ability to deal effectively with people on emotional issues and knowledge of what information to communicate and to whom. This idea is supported by Brotheridge et al. (2019). It was mentioned that emotional sensitivity is a skill in receiving and interpreting emotional and non-verbal communication. To exhibit this skill principals should understand the needs and feelings of their colleagues and establish rapport among them. Social expressiveness is ability to communicate verbally and skill in engaging others in social interaction. Social sensitivity is verbal listening skill, but also ability to “read” social situations, and general knowledge of social rules and norms. All these skills are needed in the 21^st century management.

In Table 4, the data showed that the perception of the 21^st century leadership skill of the secondary principals in terms of judgment has an over-all mean in self-evaluation of 4.41 and in the department heads evaluation of 4.36. In all of the items, the mean ranges of the self-evaluation of 4.11 to 4.67 and of the department heads evaluation ranges from 4.21 to 4.54 indicating that the secondary principals are frequently to almost always practicing judgment.

Table 4. Difference of Self-Evaluation and Department Head's Evaluation on Judgment

The data also revealed that the highest mean of the secondary school principals' self-evaluation is assigning priority to issues and tasks within the school's vision for teaching and learning, seeking to identify the causes of problems and establishing relationships between issues and events while the lowest mean of the self-evaluation are avoiding reaching quick conclusions and making decisions with limited data and using relevant sources for data and information to confirm or refute assumptions. The highest mean of the department head evaluation is assigning priority to issues and tasks within the school's vision for teaching and learning while the lowest mean is exercising caution when dealing with unfamiliar issues and individuals.

The t-test reveals that there is no significant difference between self-evaluation and department head's evaluation on judgment. This finding supports the idea that principals should have the proper capability to discern things that need to be prioritized. They should also be able to explain the rationale of their decision. According to Choomnoom (1980) judgments of administrators alone, if empirically established can be useful as a tool to establish common understanding and promote more effective operation, it would seem highly desirable that in order to reach solutions and to settle possible differences, implementation of a team effort in which others who are involved should prove to be even more effective.

Table 5. showed that the 21^st century leadership skills of the secondary principals in terms of results orientation has an over-all mean in self-evaluation of 4.67 and in the department heads evaluation of 4.45. In all of the questions the mean ranges of the self-evaluation of 4.44 to 4.89 and of the department heads evaluation ranges from 4.33 to 4.53 indicating that the secondary principals frequently to almost always practice results oriented. The data also revealed that the highest mean of the secondary school principals of the self-evaluation is taking responsibility for implementing initiatives to improve teaching and learning while the lowest mean of the self-evaluation is determining criteria that indicate a problem or issue is resolved. In contrast to this, the highest mean of the department head evaluation is taking action to move issues toward closure in a timely manner while the lowest mean is determining criteria that indicate a problem or issue is resolved.

Table 5. Difference of Self-Evaluation and Department Head's Evaluation on Results Orientation

Based on the t-test of independent events, the computed tvalue is 2.49, which is significant at .05 level. This means that there is a significant difference in the self-evaluation and department head evaluation. The result of self-evaluation and department head evaluation on the result orientation is high. This means that the principals in Nakhorn Nayok Schools are result oriented leaders. These leaders are fit for the 21^st century. Amah et al. (2013) mentioned that many organizations had benefited from result-oriented leadership. With the advent of globalization, to respond quickly and properly to environmental changes, there is a need for result oriented target setting and effective leadership of teams.

Table 6. showed that the perception of the 21^st century leadership skills of the secondary principals in terms of organizational ability has an over-all mean in self-evaluation of 4.72 and in the department heads evaluation of 4.50. In all of the questions the mean ranges of the self-evaluation of 4.33 to 4.89 and of the department heads evaluation ranges from 4.33 to 4.61 indicating that the secondary principals frequently to almost always practice organizational ability. The data also revealed that the highest mean on self evaluation are establishing time lines, schedules, and milestones and preparing effectively for meetings while the lowest mean of the self-evaluation is delegating responsibility to others. In contrast to this, the highest mean of the department head is using available resources effectively to accomplish the student learning goals of the school while the lowest mean is delegating responsibility to others.

Table 6. Difference of Self -Evaluation and Department Head's Evaluation on Organizational Ability

Based on the t-test of independent events, the computed tvalue is 2.63, which is significant at .05 level. This means that there is a significant difference in the self-evaluation and department head evaluation. Doyle (2018) stated that organizational skills are some of the most important and transferable skills an employee can acquire. They encompass a set of capabilities that help a person to plan, prioritize, and achieve his or her goals. Sperling (2017) stated that organization skills are about knowing what you want, and then prioritizing your activities and planning your time around activities that will help you achieve those goals.

Table 7. showed that the perception of the 21^st century leadership skills of the principals in terms of oral communication has an over-all mean in self-evaluation of 4.73 and in the department heads evaluation of 4.5. In all of the questions the mean ranges of the self-evaluation of 4.67 to 5.00 and of the department heads evaluation ranges from 4.42 to 4.61 indicating that the secondary principals frequently to almost always practicing oral communication.

Table 7. Difference of Self-Evaluation and Department Head's Evaluation on Oral Communication

The data also revealed that the highest mean of the secondary school principals of the self-evaluation is speaking articulately while the lowest mean of the selfevaluation is demonstrating effective presentation skills, e.g., opening and closing comments, eye contact, enthusiasm, confidence, rapport, use of visual aids, tailoring messages to meet the needs of each unique audience, clearly presenting thoughts and ideas in oneon- one conversations, and clearly presenting thoughts and ideas in communication with small groups. In contrast to this, the highest mean of the department head is speaking articulately while the lowest mean are demonstrating effective presentation skills, e.g., opening and closing comments, eye contact, enthusiasm, confidence, rapport, use of visual aids and using correct grammar.

Based on the t-test of independent events, the computed tvalue is 4.09, which is significant at .05 level. This means that there is a significant difference in the self-evaluation and department head evaluation. Since there is Miller (2019) noted that face to face conversation brings quick feedback by reading facial expression and body language and this paves the way to giving trust or not trust the one who is relaying the message.

Table 8. showed that the perception of the 21^st century leadership skills of the secondary principals in terms of written communication has an over-all mean in selfevaluation of 4.70 and in the department heads evaluation of 4.36. In all of the questions the mean ranges of the self-evaluation of 4.56 to 4.78 and of the department heads evaluation ranges from 4.25 to 4.42 indicating that the secondary principals frequently to almost always practice written communication. The data also revealed that the highest mean of the secondary school principals of the self-evaluation are writing concisely and demonstrating technical proficiency in writing while the lowest mean of the self-evaluation is expressing ideas clearly in writing. In contrast to this, the highest mean of the department head is writing concisely while the lowest mean is demonstrating technical proficiency in writing.

Table 8. Difference of Self-Evaluation and Department Head's Evaluation on Written Communication

Based on the t-test of independent events, the computed tvalue is 4.09, which is significant at .05 level. This means that there is a significant difference in the self-evaluation and department head evaluation. Blazer (1998) said that understanding writing as a dialogue has the potential to improve the written communication of school principals. Language is an important element of the social construction of meaning in organizations, and writing is an opportunity for principals to facilitate the process of sense making in a school community.

Table 9. showed that the perception of the 21^st century leadership skills of the secondary principals in terms of development of others has an over-all mean in selfevaluation of 4.20 and in the department heads evaluation of 4.47. In all of the indicators, the mean ranges of the self-evaluation of 3.89 to 4.56 and of the department heads evaluation ranges from 4.25 to 4.47, which shows that the secondary principals frequently to almost always practice developing others. The data also revealed that the highest mean of the secondary school principals of the self-evaluation is suggesting specific developmental activities to improve others' professional capacity to contribute to student learning while the lowest mean of the self-evaluation is asking a protégé what he/she perceives to be strengths and weaknesses and what he/she wants to improve. In contrast to this, the highest mean of the department head is sharing information and expertise from my professional experiences to assist the professional growth of others while the lowest mean is asking a protégé what he/she perceives to be strengths and weaknesses and what he/she wants to improve.

Table 9. Difference of Self-Evaluation and Department Head's Evaluation on Development of Others

Furthermore, the t-test reveals that there is no significant difference between the self-evaluation and department head's evaluation on the development of others. Bredeson (2000) said that the school principals' leadership in the area of teacher professional development is critical to the creation and success of a school learning community. Therefore, this skill should not be neglected and principals should give attention to continuous professional development.

Table 10. showed that the perception of the 21^st century leadership skills of the secondary principals in terms of understanding own weakness and strength has an over all mean in self-evaluation of 4.67 and in the department heads evaluation of 4.47. In all indicators, the mean of the self-evaluation have the same mean of 4.67 and of the department heads evaluation ranges from 4.38 to 4.55 indicating that the secondary principals frequently to almost always practice understanding own weakness and strength. The data also revealed that secondary school principals find themselves the same in all the indicators namely: recognizing and appropriately communicating principal's own strengths, recognizing and managing developmental needs and actively pursuing personal growth through participation in planned developmental activities. In contrast to this, the highest mean of the department head is actively pursuing personal growth through participation in planned developmental activities while the lowest mean is recognizing and appropriately communicating the principal's strengths and weaknesses.

Table 10. Difference of Self-Evaluation and Department Head's Evaluation on Understanding Strengths and Weaknesses

It is revealed that the capability to understand strengths and weaknesses based on self-evaluation is significantly different with the department head's evaluation with a mean value of 4.67 and 4.47, respectively. T-Test value of 3.95 shows that there is a significant difference between the self and department head's evaluation. The principal rated themselves as higher than the rating of their department head. However, the rating is still high, meaning the principals in Nakhorn Nayok still fit this 21^st century skill. This finding that principals rated themselves higher that their department heads is supported by Goleman (2001) that better performers are more likely to accurately assess their abilities or underestimate their abilities, average performers typically overestimate their strengths.

The result of this study is supported by the analysis of Huang (2013) that those who are capable of recognizing their own strengths and weaknesses are in a competent position of identifying and managing others' needs thus this 21^st century leadership skill indicator is essential.

The self-assessment shows that the principal rated himself as high quotient. Similarly, the department heads also rated their principals as high in their 21^st century leadership skills quotient. Specifically, it was also found out that there is no difference in the self-assessment in the following indicators: setting instructional direction (t_.05 =0.95), teamwork (t_.05 =0.49) sensitivity (t_.05=1.0409), development of other (t_.05 =1.614) and, results orientation (_t.05 =0.95). However, it was found out that there is a difference in the following indicators: oral communication (t_.05 =4.097). judgment (t_.05 =0.65) organizational ability (t_-.05 =2.63) written communication (t_.05 =4.097), understanding strengths and weakness (t_.05 =3.95).

According to the National Association of Secondary Principals (NASSP) assessment tool, if there is a significant difference of the leadership quotient of principal as assessed by themselves and by their department head, this should be given attention in terms of development.

Table 11. Summarizes the Fndings on the Principals' 21^st Skills Quotient Based on Self- Assessment (4.57) and Department Heads Assessment (4.49).

As gleaned in Table 12, there is high correlation of the selfassessment and department heads' assessment on the 21^st century skills of the principals. It can be noted Pearson's r test showed a value of .468 at .01 level of significance. This shows that the principal's self-assessment has high correlation with the department head's peers' rating. This shows that peer evaluation is a valid way to assess the principals' 21^st century skills quotient.

Table 12. Correlation between Self-Assessment and Department Heads Assessment of the Principals' 21^st Century skills

The findings of this research corroborates with the findings of a research by Turrentine (2001) on the comparison of leadership skills of the members of a residential leadership community. The self-rating were compared with the responses of peer observers. Self-reports of leadership practices were confirmed by peer reports in 72% of cases. Self-assessments of the quality of performance were confirmed by peer assessments in 83% of cases.

Sharma et al. (2016) noted that self-assessment can increase the interest and motivation level of students for the subjects leading to enhanced learning and better academic performance, helping them in development of critical skills for analysis of their own work.

Table 13 shows the skill development needs of principals in the 21^st century leadership skills as perceived by themselves and their department heads. It was also found out that the first needed skill to be improved based on the ranking by themselves is rank 1: Setting Instructional Direction (2.28), followed by rank 2: teamwork (2.63), rank 3: Judgment (3), Result Orientation (3) and Development of Others (3), rank 4: understanding strengths and weaknesses (3.75), rank 5: Organizational Ability (4) and Sensitivity (4) and lastly, rank 6: Oral communication (5) and written communication (5). While the head teacher thinks that the principal needs to develop first, rank 1: teamwork (2.69), followed by rank 2: understanding strengths and weaknesses (2.85), rank 3: Setting Instructional Direction (2.92), rank 4: Result Orientation (3.02), rank 5: Development of Others (3.10), rank 6: written communication (3.12), rank 7: Organizational Ability (3.17), rank 8: sensitivity (3.23), rank 9: Judgment (3.42) and rank 10: Oral communication (3.50).

Table 13. Improvement Needs of the 21^st Century Leadership skills of the Principals

Furthermore, the mean rank of the 21^st century skills is also shown in Table 13 and the summary of ranking shows that the 21^st century skill that should be prioritized would be team work, setting instructional direction, understanding results orientation, results orientation, and development of others which are ranked 1 to 5, respectively. However, the rest of the 21^st skills were still chosen for further development thus these skills should not be neglected when skills training and development are to be done.

According to the results in Tables 12 and 13, there is a match in the priority skills to be given attention and these are results orientation and understanding of strengths and weaknesses. Though the other skills are not prioritized, these skills should not be neglected because there is interconnection among these skills.

Discussion

The results of the study show that the principals rated themselves high in the all the indicators of the 21^st century skills and this is attested by the assessment done by their department heads who work with them closely. However, according to the assessment tool, if there is any significant difference in the self and peer assessment, this is an area of concern, which implies that there is a need for continuous program on the 21^st century skills development for administrators. Based on the ranking, the skills that need immediate attention are teamwork, setting instructional direction, understanding the strengths and weaknesses, results orientation, and development of others. However, the skills such as judgment, organizational ability, written communication and oral communication and sensitivity are least priority, but is does not mean that they should be neglected. The scores attained are not perfect thus there is a lot of room for improvement of these 21^st century skills. There is also high correlation of the self-assessment and department head assessment. This shows that peer assessment is reliable way to track deterioration and/or improvement. However, the study may have its limits on the influence of camaraderie on the scoring, but if the assessors are sincere in their evaluations then this helps improve leadership and trickles down to the other stakeholders of the school.

Based on the results of the study, the principals' 21^st century skills quotient in all the indicators are high in both selfassessment and department heads assessment. The principals have the necessary skills to lead their schools. It was also found out that self-assessment and department head's assessment have no difference in some skills, but has difference in the other skills. There is a need to improve some skills with different of the 21^st century leadership skills of the secondary school principal as perceived by themselves and their department heads. The skills related to teamwork, setting instructional direction, understanding strengths and weaknesses, results orientation and development of others should be given priority for development. However, the department heads and principals still consider skills development in the other indicators namely: judgment, organizational ability, oral and written communication, and sensitivity. Self assessment and department head assessment have high correlation therefore, regular peer assessment can be done to track the principal leadership skills if they are maintaining them to the standard for continuous improvement.

Recommendation

It is therefore recommended that there should be a designed process for continuous training on the 21^st century skills among the secondary principals of Nakhon Nayok together with their department heads. Continuous training can only be done if a model plan will be prepared based on the skills related to teamwork, setting instructional direction, understanding strengths and weaknesses, results orientation and development of others. The systematic learning opportunities should be created for the principals to help them develop these complex skills needed in order to lead and transform contemporary schools. The principals should develop “professional capital” by sharing and learning the best practices from each other by benchmarking both internally and globally which is an essential skill called collaboration in this modern school settings. Lastly, secondary school principals should consider getting opportunities for global networking and dialogue to realize improvement/progress in leadership. The tool can be used to assess also other school administrators' 21^st century skills.