The study aimed to use the strategy of visual thinking networks in teaching biology to develop the depth of scientific knowledge among first-year secondary school students. The study group consisted of (35) female students in the first year of secondary school at Dagwa Combined Secondary School affiliated with the Banha Educational Administration in Qalyubia Governorate, and the fourth chapter was chosen ( Classification of Living Organisms) from the Biology textbook for the first year of secondary school. The teacher’s guide and worksheets were prepared for the student in the chosen section. The study tools were: (the depth of scientific knowledge test). The study tools were applied before and after on the study group, and results were obtained. The study includes the following:
1- “There is a statistically significant difference at the level of significance (0.01) between the average scores of the students in the experimental and control groups in the post-application to test the depth of scientific knowledge as a whole and at each level separately, in favor of the scores of the students in the experimental group.”
2- “There are statistically significant differences at the significance level (0.01) between the average scores of the experimental group students in the pre- and post-applications to test the depth of scientific knowledge as a whole and at each level separately, in favor of the post-application scores.”