Textbooks are a fundamental part of classroom instruction. Over 90% of teachers have reported using textbooks in some form, and exposure to textbook material can influence student's [sic] self-concept. However, the use of illustrations that only represent one group prevents diverse role modeling. This, it follows that the provision of diverse illustrations increases student capacity to develop self-concept. For example, highlighting female illustrations in a textbook increases a female reader's self-perception in that subject. Historically, science textbooks have been found to be gender biased, showing males more frequently than females (Heikkinen, 1978). A review of illustrations in high school chemistry textbooks from the 2010s found that male illustrations continue to be used more frequently than female illustrations. This study revealed a statistical significance in the difference in total frequency of male and female illustrations in high school chemistry textbooks from the 2010s. Even so, five of the seven chemistry textbooks from the 2010s did not differ significantly in male and female illustration frequency. Illustrations in chemistry textbooks from the 2010s did not exhibit stereotyping, with one gender performing science-related actions more frequently than another. Ultimately it was found that although high school chemistry textbooks from the 2010s had a reduced gender role compared with chemistry textbooks from the 1970s and 1980s, gender bias still existed.