Boris Yarmakhov, and Sergey Sumatokhin. “A DIGITAL ADAPTIVE TEXTBOOK FOR SECONDARY BIOLOGY EDUCATION: DEVELOPMENT AND TESTING: Received: 12th March 2026, Revised: 22th April 2026, Accepted: 05th May 2026, Date of Publication: 12th June 2026”. PUPIL: International Journal of Teaching, Education and Learning, vol. 10, no. 1, June 2026, pp. 20-29, doi:10.20319/pijtel.2026.101.2029.