According to previous studies, there is an average of 8.3 analogies in elementary and
high school science textbooks in the United States (Curtis & Reigeluth, 1984), an average
of 9 analogies in high school chemistry textbooks in Australia (Thiele & Treagust, 1994),
and an average of 12.5 analogies in school physics textbooks in Turkey (Yener, 2012).