1.8 Definition of key terms
The following definitions are included to clarify the terminology that used in this study:
1.8.1 Teaching vocabulary
Importance of Vocabulary:
Vocabulary is an important element in learning a language. Knowing words helps learners to communicate through target language better. Many researchers such as Maximo (2000), Read (2000), Gu (2003), Marion (2008), and Nation (20011) have focused on the importance of vocabulary acquisition and its essential role in learning a second successfully, and its importance in the formation of written and spoken skills. Regarding to the importance of vocabulary Shen (2008) argued that EFL/ESL language abilities are greatly related to learners' vocabulary knowledge. Nation (2011), discussed
Schmitt (2008) said the ideal approach for learning vocabulary has not found yet. So choosing the most practical and appropriate method is not an easy task. There are variety of methods and techniques in vocabulary instruction. Methods differ for different learners based on learners' need, ability, level, age, and their background knowledge. Strategies and techniques which are used in the class by educators should make an enjoyable and practical atmosphere for both learners and teachers. There are different techniques in teaching vocabulary that they will be discussed broadly in the next
According to this handbook Down syndrome is the world's most common chromosomal disorder and it is the reason of intellectual disability. Here is mentioned that Down syndrome is not an illness or disease, it happens in one of every 700 to 900 birth around the world (2009, p.6). In the preface of the handbook developmental profile for learners with Down syndrome is introduced which is developed by Professor Sue Buckley and colleagues at Down Syndrome Educational International (http://www.downsed.org). This profile gives on overview related to learning skills, strengths and weaknesses which are associated with Down syndrome. Based on information on this profile the definition of Down syndrome is a chromosomal disorder which results in different level of physical, health, and intellectual difficulties. It is also mentioned that this matter is caused by the presence of full or partial extra copy of chromosome 21 which is known as trisomy 21 too. This additional genetic material changes the process of development in individuals with extra chromosome and causes characteristics associated with Down syndrome. Common features of Down syndrome according to Health Genetics journal