The emergence of new Information and Communication Technologies (ICT) has led to rapid expansion across a wide range of areas in the modern world. This rapid growth in the use of technology in the 21^st century has profoundly changed our daily life. At first, computers were introduced and later on their portable versions (laptops), IPods, tablets, and then smartphones were presented (Sampson, Isaias, Ifenthaler, and Spector, 2013). Nowadays, students have grown up in a media culture and the Internet, computer games, email, and cell phones are integral parts of their lives. This use of technology tools in all aspects of human life in the last decade has led to its growing presence in educational settings (Baran, Uygun, and Altan, 2016). Thus, information and communication technologies have paved the way for educators and teachers to create distance learning and online learning environments that improve the entire teaching and learning process (Martiz, 2015). From this perspective, it is safe to conclude that applying technology to the learning is becoming an important educational issue today. Even though Iran is still in the infancy stage in implementing teaching and learning using technology, many universities and schools in here are transforming themselves to be an electronic university in future.

Online learning is one of the fast-growing trends in education settings, especially at higher education institutions. Thereby, Khan (2014) defines online learning as “an innovative approach for delivering well-designed, learner-centered, interactive, and facilitated learning environment to anyone, anyplace, anytime by utilizing the attributes and resources of various digital technologies along with other forms of learning materials suited for open, flexible, and distributed learning environment” (2005, p. 3). One of the most common approaches that have been widely used in technology-driven language learning and teaching environment is blended learning. Blended Learning (BL) is identified as an innovative learning model that encourages students to engage with technology in a student-centered approach (Poon, 2013). According to MacDonald (2008, p. 2) blended learning “is commonly associated with the introduction of online media into a course or programme, while at the same time recognising that there is merit in retaining face-to-face contact and other traditional approaches to supporting students”.

According to Butler (2013) with continuous advancement of technology tools, web-enabled tools like computers, tablets, and smartphones can provide ample opportunities for enhancing learning. Enhancing language learning opportunities needs special attention to those aspects which form the bases of language among which is vocabulary acquisition. Vocabulary learning is regarded as the key basis for the instruction of English as a second language and it is a backbone of all language skills: reading, listening, writing, and speaking (Wang, Zou, and Xing, 2014). Thus, the key to success in acquiring and learning every language is the acquisition of its vocabulary. Without extensive vocabulary knowledge, even those who show mastery of grammar might experience the failure to communicate. Both teachers and L2 learners are now encountering difficulties among English vocabulary learning (Pazio, 2010). It seems that many Iranian students still struggle with their poor mastery of English vocabulary. Although they took courses in English from early years, they cannot communicate in English properly. Therefore, it could be contended that vocabulary teaching and learning deserves more attention in the EFL context of Iran.

Furthermore, Shams (2013) stated that CALL and MALL approaches have been widely adopted at schools and universities, but its effectiveness and integration with conventional teaching models are still unclear. This lack of clarity makes the motivation of this research to evaluate the efficacy of blended learning in improving English vocabulary knowledge in Iranian EFL context. While there has been considerable research on blended learning, most of this has been conducted in the west. Although blended learning is currently gaining attention, it is still not well-developed and few studies (Aslani and Tabrizi, 2015; Ghazizadeh and Fatemipour, 2017; Shams, 2013) have proved the success and advantages of blended learning in learning language skills and subskills in Iran. Therefore, in the continuation of the cited studies, the purpose of the present paper is to examine the possible differences of learning vocabulary items by Iranian students through different models of learning (traditional and blended). It also attempts to explore the students' perceptions and attitudes towards blended learning approach with engagement in social networks and smartphones applications in learning vocabulary. Therefore, the following research questions guided the present study:

• What are the effects of the blended learning strategy via Memrise application in teaching vocabulary on Iranian students' vocabulary knowledge in comparison with the f2f method?
• What are the students' perceptions and attitudes towards blended learning instruction?

There have been many methods of teaching English, and also many learning strategies used in teaching the English language. Although, with the rapid growth of technology, one of the most common approaches that have been widely used in technology-driven language learning and teaching environment is blended learning (Butler, 2013). The Transactional Distance Theory (TDT) is a theory behind the blended learning. It was the first pedagogical theory, by Dr. Michael G. Moore in 1970, derived from analysis of teaching and learning conducted through technology (Graham and Allen, 2009). TDT is promoted as a way of analyzing learning and teaching by looking at it as the separation between learners as well as between teachers and learners in distance education. With separation, there is a psychological and communications space to be crossed that is transactional distance. TDT emphasizes on the psychological and communications distance that is bridged through course structure, learner autonomy, and dialogue (Moore, 2013).

Moreover, Graham (2006) predicted that the use of Blended Learning (BL) will continue to grow, and it is important to have a better and obvious understanding of the phenomenon of blended learning. The year 2006 marked an important milestone for the historical development of the term blended learning with a new publishing of the first Handbook of Blended Learning. In the first chapter titled “Blended Learning Systems: Definition, Current Trends, and Future Directions”, the author Charles Graham reviewed all previous broad kinds of BL definitions and then focused on speaking of blended learning systems (Graham et al., 2014). He used the idea of “BL is combining online and F2F instruction” as a foundation for his own definition: “Blended learning is the combination of instruction from two historically separate models of teaching and learning: traditional F2F learning systems and distributed learning systems. It also emphasized the central role of computer-based technologies in blended learning” (Graham, 2006, p. 7). Because of this clear explanation, Graham's definition of BL became to be broadly accepted. In the words of Graham and Allen (2009), some researchers defined BL as a mixture of face-to-face instructor led and self-paced online learning (Graham 2006), while some educational researchers believed BL should include the use of mixed media (Osguthorpe and Graham, 2003).

The term “blended” has abroad meaning and it contains the integration of e-learning and traditional learning. The blend of these learning methods depends on the needs of the students, the online materials, and the instructor requirements (Khan, 2014). Blended learning is a contested term that spans a continuous between fully online and face to face learning, i.e. between 0 and 100% of electronic delivery. Thereby, there are many different models and blended learning methods for delivering training, but no certain rules to define what the ideal blend might be (Hewett, 2016). More specially, the emphasis is not on selecting the best, right, or innovative blended; rather, it is about developing an optimal blended learning that exploits the best of the available modes (Graham and Allen, 2009). This issue has motivated by Twigg (2003) to identify five distinct course design models of blended learning approach: supplemental, replacement, emporium, fully online, and buffet. A key differentiator among them is the face-to-face ratio to the online time of each model distributed in a course. Similarly, Staker (2011) identified six blended learning models: face-to-face driver, rotation, flex, online lab, self-blend, and online driver, which each including design elements that distinguished them from the others. These models are presented in Figure 1,a spectrum of definitions, in the one extreme of the spectrum a small online supplement to a traditional course can be used; in the other extreme a fully online learning is provided. It is worth pointing out here that the supplement model of Twigg (2003) or the face to face driver model of Staker (2011) is used in the current study.

These models enable learners to synchronously and asynchronously access and transfer data, interact and collaborate with peers (Graham, Henrie, and Gibbons, 2014). According to Hrastinski (2008), in synchronous learning, learners and teachers communicate online at the same time from different places. Therefore, the teacher and the students can see each other during learning (Hrastinski, 2008 as cited in Alqahtani, 2010). However, in the words of Sussman (2006), in asynchronous learning, students and teachers do not require to be online at the same time, communication among participants can be self-paced and self-directed, and allow the students to do their learning at their own pace and own time over a prespecified period for doing their activities (Sussman, 2006 as cited in Alqahtani, 2010).

The appearance of new technologies, such as computers, IPods, and especially mobile devices can support learners in learning vocabulary items. Wang, Zou, and Xing (2014), defined mobile devices and smartphones as wireless technology that is not restricted to a specific location. They also can support opportunistic and collaborative informal learning among learners. Consequently, the appearance of mobile devices in language learning resulted in developing mobile applications (apps). Mobile apps are software applications designed and developed to install on mobile smartphones or tablets. The mobile apps are designed to be fast and efficient; allow learners for reaching a rich content in form of digital materials, simulations, and learning games (Lindaman and Nolan, 2015). The asynchronous blended learning of the current study has been designed using one of the free web-based application called Memrise. It is one of mobile applications (apps) to learn vocabulary words integrated into the supplementary blended learning model.

Ample studies (Alshwiah, 2010; Shams, 2013; Ghazizadeh and Fatemipour, 2017; Khazaei and Dastjerdi, 2011; Pazio, 2010) were conducted in blended learning approach, particularly focusing on the benefits of blended learning, students' experiences and attitudes towards blended learning, and a comparison of conventional face-to-face learning, blended learning, and online learning. The results of which were highly influential for those interested in using technology-driven language learning and teaching materials. Some studies show blended learning is more effective than traditional face-to-face learning, while others show no difference between students' performance in traditional blended learning classes. Moreover, the results of several research studies of students in higher education settings revealed that student satisfaction and learning outcomes can be higher in blended learning environments.

Figure 1. Blended Learning Spectrum of Definitions

The participants in this study included 40 students (30 BA and 10 MA) from a university in Iran. These participants were both male and female and their age ranged from 20 to 43 years having university degrees in different fields of education. By administering DIALANG proficiency test, those students who demonstrated intermediate proficiency in English vocabulary knowledge (Level B) were identified. Then, participants were randomly assigned to a control group and an experimental group.

The instruments used in this study to collect quantitative and qualitative data are explained as follows.

This instrument was an online diagnostic test, which was called DIALANG the link of which was http://www.dialang.org sent to the participants via a Gmail to determine language learners' proficiency level in English. The test in each language is divided into three parts after which the examinees are assigned into different proficiency levels. Learners' proficiency in different language components (grammar, vocabulary) and skills (listening, reading, writing, and speaking) is diagnosed in the form of scores related to the Common European Framework of Reference for Languages (CEFR). Based on these scores, the examinees were assigned into one of CEFR levels from A, B, and C. Participants were informed that only their level in vocabulary proficiency is of importance for these study purposes. Thus, they were requested to do the vocabulary test and the learners whose proficiency level was intermediate (B) were selected as a sample of this study.

The pretest consists of 40 word items in the form of multiplechoice questions, from a vocabulary book is called “400 must have words for the TOFEL” by McGraw-Hills, which examines the learners' initial knowledge of the first 400 words of TOEFL, an intermediate English course, in the two groups (control and experimental) and the same test was used for the post-test. Reliability and Validity are important concepts in research as they are used for enhancing the accuracy of the assessment and evaluation of a research work. In this study, a test reliability Cronbach's alpha coefficient of internal consistency was used that examined single test administration to provide a unique estimate of the reliability for a given test. Cronbach's alpha is a value between 0 and 1. Values close to 0 indicate low reliability and values close to 1 indicate high reliability (Creswell, 2014). The reliability of the vocabulary pre-test was 0.78 (Cronbach's alpha), which claimed that the reliability of this test was good. It was calculated in Statistical Package for the Social Sciences (SPSS) software as shown in Table 1.

Table 1. Cronbach's Alpha Reliability Coefficient

Memrise is an online learning computer-based application with courses created by its community. Its courses are mainly used to teach language, but are also used for other academic and non-academic subjects, including science, music, history, philosophy, and popular culture. It is available as a web app, as well as on android and iOS devices to facilitate the mastery of vocabulary items, basic phrases, and sentences. Memrise teaches words by first showing students meanings, concepts, pronunciations, and then speed reviews are like short quizzes with multiplechoice questions in which their knowledge is tested under timed conditions. The immediate feedback is also provided after each single question while taking the quizzes, such that the right option is marked in green color and the wrong answer is marked in red color. There are a number of reasons for selecting Memrise app: First, the application is free to use and allow for simple account creation. Second, a course can be created on Memrise by uploading content into its courses. In the Memrise application, items can be arranged in user generated courses. Finally, this app has many language translations to all the words in the course (Memrise Inc, 2013).

The qualitative data of the study was obtained from the semi-structured interviews, including a few free-flowing questions, which was conducted for students from the experimental group in order to identify their views on blended learning. The semi-structure interview has been selected for this study because it reserves rooms for open-endedness that may be needed for providing a better explanation on the answers by the interviewees (Dornyei, 2007).

This study adopts mix-method approach design, which combines qualitative and quantitative methods to examine the possible differences of learning vocabulary items by Iranian students through different models of learning (traditional and blended). The learners utilized a freely accessible multimedia web-based application (Memrise) in a supplemental model blended learning context. The participants were introduced in Persian to Memerise app via their Telegram accounts. The course used in this study is the first 400 words of TOEFL, an intermediate English course, which could help the learners to be successful in the TOEFL exam. The first 400 words used in the Memrise course ran parallel with the content being taught in the classroom. Therefore, the control group were taught vocabulary items through the face-to-face way of teaching with six in-class hours per week and the experimental group took the form of a combination of face-to-face classroom teaching with using Memrise application asynchronously outside the scheduled class time. After 4-weeks of the instruction period, students were learned about 260 words of the first 400 word items, then the two groups took the post-test. To be sure that participants studied the words of their level, the researcher requested them to send screenshots on app's pages (See Appendix A). The students' perspectives on the use of mobile app in blended method were shown by the findings of interviews.

The first research question was answered using data obtained from the evaluation pre-test and post-test, the means and the standard deviations of control and experimental groups on two tests were compared and contrasted. Using the Statistical Package for the Social Sciences (SPSS), independent sample t-test was used to analyze pre-test and post-test scores. In other words, the scores of the students in pre-test were compared with the scores of the students in the post-test in the two groups to decide how much improvement has been made. The students' perspectives on the use of mobile and technology tools were shown by the findings of interviews. Among the participants, 5 students from the experimental group were selected based on the high scores in their pretest and post-test. Students' interviews were recorded and transcribed respectively in Persian and English. On an average each interview lasted about 20 minutes. During the process, follow-up questions were asked in order to gain more insights into participants' responses. Qualitative data analysis began with coding and proceeded in creating categories (themes). The process of coding the focus group transcripts included a manual system of open coding as described by Creswell (2014) to categorize themes during which the author writes to pull out meanings and then connect those meanings to arrive at explanations and interpretations.

What are the effects of the blended learning strategy via Memrise application in teaching vocabulary on Iranian students' vocabulary knowledge in comparison with the f2f method?

To answer the first research question, an independent sample t-test was conducted using SPSS software to compare mean of the two groups of the study sample in pretest and posttest. The independent sample t-test was also used to determine whether the difference in means between the two groups – if it existed – was significant at the alpha level (0.05). The two hypotheses for this analysis state:

H0 : There is no significant difference between means of two groups in pre-test and post-test

H1 : There is a significant difference between means of two groups in pre-test and post-test

Table 2 illustrated the values of means, standard deviations, and standard error means for each group. The performance of participants of the control group was (M = 24.50, SD = 3.98, SEM= 0.89) and the experimental group was (M = 24.15, SD = 3.87, SEM= 0.86). The pretest means of the two groups were analyzed for significant differences.

To determine whether this difference between the pre-and the posttests is statistically significant, a t-test was applied as shown in Table 3. The value of (F) would be 0.006, and the level of significance would be 0.938 (p = 0.780 > 0.05), indicating no significant difference between the research sample groups with regard to their vocabulary knowledge in pre-test.

Table 4 shows the difference between the means of the two groups, which can be inferred that experimental group had a significant improvement in the post-test. In other words, comparing the mean standard deviation, and standard error mean of the control group in the post-test (M = 25.85, SD = 2.24, SEM= .950) and the experimental group (M = 28.85, SD = 4.23, SEM= 944), it was apparent that second group had better performance after using the blended app.

The results (Table 5) measured by the independent samples t-test showed that the value of (F) would be 0.069, and the level of significance would be 0.795, (p = 0.031< 0.05), which had statistically significant differences between the research sample groups in the post-test. Furthermore, it is safe to declaim that this study rejected the null hypothesis, which suggests that there is no significant difference between the achievement of the students who have used blended learning and the achievement of the students who have used traditional learning method. And it supported the alternative hypothesis that students who participated in blended group will have significantly higher scores than those enrolled in traditional face-to-face class.

Generally, in Figure 2, the mean of two groups in both tests have been comparatively illustrated. It is clear that the mean of experimental group is greater than the mean of control group in the posttest, which indicates that there is a significant difference between the two groups of learners with regard to their vocabulary knowledge after 4-weeks of blended instruction period.

What are the students' perceptions and attitudes towards blended learning instruction?

To answer the second research question, semi-structured interviews were conducted, which is looking for the attitudes of students who used blended learning method via Memrise app in learning the first 400 words of TOFEL. Interviewees' background information and their pseudonyms are displayed in Table 6.

Open-thematic coding was the method used for this purpose. Therefore, three themes emerged in this study included: 1) participants' reasons for using the blended learning which somehow implied its positive aspects, 2) any shortcomings in the blended method perceived by participants which revealed their negatives aspects, and 3) participants' suggestions for promoting the blended learning approach.

The interview questions, the coding system, and illustrative segments from interviews are presented in Table 7. The guiding questions were 6, which were used along with follow-up questions came up during interviews sessions, they were as follows:

• What were the main advantages and disadvantages of using blended learning method in learning vocabulary?
• What were some specific difficulties that you had during using this blended learning?
• What do you think of using this method of learning at the university level?
• What is your overall attitude toward using blended learning method?
• Do you prefer to use CALL (Computer Assistant Language learning) or MALL (Mobile Assistant Language Learning)?
• What recommendations do you make about the blended learning method?

Both positive and negative views were received about the student vocabulary learning experiences using blended method via Memrise app. Some examples are presented in following:

“I found the time was flexible. I could study whenever and wherever I wanted, even at night or noon and at work when I was free. I believed this method is flexible in terms of time as it left the learner to choose the suitable time for learning at his/her convenience. As I used the online app at a suitable time and place, the blended learning course was convenient. I think that with blended learning I will be able to manage my own studying process by arranging my time accordingly.” (Mohana)

Also an accounting student expressed her opinions about being an active student in blended learning method:

“I think this blended method was very different and unique because it constituted active learning. I was active in my learning by downloading the online blended app to my computer for the convenience of learning vocabularies. In traditional classroom, I accepted knowledge passively rather than actively being engaged in knowledge construction. Indeed, my improvement was due to being more engaged in my learning process. For me, the course was suitable and easy to follow. I think the course met my expectations somehow and I was satisfied”. (Mohana)

Besides mentioning a fair number of positive aspects about the blended learning method by using Memrise app, negative aspects had also been discovered by them. These negative points were targeted to the limited interaction and the use of ICT tools.

“I found that blended learning occurred completely independent and with the absence of the course teacher when I used the app outside the class. Also there was a limited direct interaction between students and teachers. I think this limited interaction between students, between students and teachers compared to traditional training class was the most disadvantageous part. I didn't like fewer the less interactions between students and the teachers. It led me to forget what I had learnt because I liked to receive my teachers' feedback in form of comments after taking part in a test.” (Mohana)

Other obstacles and problems related to use of ICT tools were expressed by Samira and Hamed:

“The blended method occurred completely independent and with the extension of materials and learning outside the classroom, the self-control, guiding, and monitoring in blended learning environment were decreased by distractions of available technologies for me. I didn't have my selfcontrol and I was vulnerable to interference with online information unrelated to learning when I was studying online app which resulted in efficiency reduction of online learning.” (Samira)

At last, some students' suggestions for improving the efficiency of blended learning and the usefulness of blended method are presented.

“In my opinion the various and diversified resources are available for learners when using the blended learning method and it would be very helpful by creating opportunities for students to access online course materials which were rich and easy to learn. These authentic resources apart from the teacher include online books, websites and the various files associated with the course. I'll use all of the online resources and try to make the most use of them in order to get the best results from the TOFEL test. I think these resources tend to make blended learning an excellent method for teaching and can support students learning.” (Zahra)

Also Mohana preferred a useful technology device in blended learning method.

“I liked to use of the application on my smartphone. I think that mobile phones have become a more accessible and affordable tool for communication and learning than personal computers and they make learning possible anytime anywhere. My mobile phone gave me opportunities to practice vocabularies at virtually anywhere, anytime in useful and convenient ways. Thus, I think that mobile learning has great potentials for providing students with rich and authentic experiences both in and outside the classroom. However, I think student ownership of the Internet connected mobile devices is very common in Iran today.” (Mohana)

Moreover, the use of blended courses for work and future qualification was of interest for some students:

“I think blended learning is suitable for people who work and study at the same time. In fact, I don't have much time. I am having a job in a company so I have a lot of work to do and I don't have time to go to a class. Attending this course, the time can be flexible and I can study at night or in the morning, whenever I can arrange and study wherever I want. I hope that all parts of the English course will be studied through blended learning method because it is very useful. I think that the blended learning courses would be useful to my work, both current and future, as well as to future study.” (Hamed)

By and large, despite a few negative experiences and some limitations, most participants' comments on the online components of the blended learning program were rather positive with most attention being paid to the blended method and online app. The findings revealed that the participants identified several main benefits to the blended learning environment, including its flexibility and convenient timing, its systematic and personalized learning, as well as some suggestions with regard to the usefulness and the use of various sources in blended learning. However, they also had identified a few obstacles and problems of blended learning, such as limited direct interaction, problems, and inefficiency in using ICT tools.

Generally speaking, different expectations were reported by participants in various parts of these interviews. It has been revealed by language teachers that diverse media provision by CALL and MALL, aids learners to acquire more (Lindaman and Nolan, 2015) as suggested by participants here in form of using various online resources. These findings are in line with Hoang Vu's (2014) study in which many of participants had positive attitudes towards blended learning in terms of timing, experiencing new technology, quality of course, and accreditation. Similarly, the findings of this study are in line with those of Malmir et al. (2016), which investigated using social networks on vocabulary acquisition among Iranian EFL learners' attitudes and concluded that Iranian students have better attitudes towards the use of social networks at the English classes. The results of which are in line with the present study. However, McCutcheon et al. (2015) evaluated the impact of blended learning vs. face-to-face learning of clinical skills in undergraduate nurse education. The results revealed that online learning for teaching clinical skills is not effective than traditional means, which is somehow in contrast to this study's finding.

Table 2. Descriptive Statistics of the Pre-test on Vocabulary Knowledge

Table 3. Independent T-test for Control and Experimental Groups on Pretest

Table 4. Descriptive Statistics of the Post-test on Vocabulary Knowledge

Table 5. Independent T-test for Control and Experimental Groups on Posttest

Figure 2. The Mean of Scores in Two Groups in Pre-test and Post-test

Table 6. Interviewees' Background Information

Table 7. Themes, Codes, and Segments Extracted from Interviews

The present study was mainly an exploratory descriptive research quantitatively and qualitatively investigating the effects of blended method on expanding vocabulary knowledge of EFL Learners. In order to understand the differences between the two groups of the study, pre-test and post-test and then the semi-structured interview were performed. Thus, the mixed method is conducted to explore in depth how students manage their own learning on a Blended Learning course at Lurestan University. The results of the study confirmed that the learning vocabulary through Blended Learning model had a positive impact on the students' vocabulary knowledge, and it was shown that most participants had positive comments on the blended method and the online app. In other words, the results of this study indicated that the proposed Blended Learning strategy improved the students' achievement and changed their attitudes towards learning English language. To conclude, this study makes a contribution to the fields of CALL and MALL as well as applied linguistics. As students in this study had no prior experiences in Blended Learning environments, the results revealed that they have somewhat different views around the influence of blended learning which were not reported in the literature. The findings of this study also could be utilized in evaluating the blended online learning from a pedagogical point of view and presents helpful insights to L2 teachers, learners, and syllabus designers. The results have practical implications for language programs and language teachers when designing a blended course. For example, they identify to what extent online materials be integrated into the blended course.