Research shows that students in Turkey are taught to write with much smaller vocabularies than students in other countries. Along with the constructivist approach, the frequency of words used in texts should be high, and unknown words should be at certain levels in order to allow for production, cognizance and creation of information based on existing information. The aim of this research is to analyze the vocabulary in Turkish textbooks before and after the introduction of the constructivist approach on the basis of frequency and origin.
The research was conducted using a general screening model composed of the words used in informative texts in Turkish textbooks before and after the introduction of the constructivist approach. With the aid of random sampling, informative texts with "Nature and Universe" themes that were used in 2001-2002 and 2013-2014 in secondary schools were chosen as samples. Frequency and percentage proportions were made in a descriptive way in order to compare the numbers of the same and different lemmas. T-test and Mann Whitney U test were used to determine meaningfulness.
While there is not a significant difference in frequency between TBCA and TACA in the Turkish, Arabic, Persian and western-based words. It has been determined that, among words that do not have synonyms, the same book after the introduction of the constructivist approach shows a preference for words used with less frequency.
Implications for Research and Practice:
The word lists for each level should be made in the context of frequency of use in textbooks.
Keywords: Word frequency, word origin, lemmas, word frequency lists.