Depression may essentially influence cognitive function contributing to poor school performance. The
present study undertakes to determine the existence and strength of correlation between depressive
symptomatology and other mental conditions with the acquired level of understanding of Newtonian
physics taught in schools. The current study recruited 490 students (262 girls, 228 boys) attending
the first semester of the Greek Second Grade of General Lyceum School. Force Concept Inventory (FCI)
tested the depth of the students’ understanding of Newtonian Physics. Symptom Checklist-90-R
assessed general mental status. The tests took place in the classroom during a 1 h session. Low FCI
scores significantly correlated with mental conditions, with depression ranking first. Girls had
higher scores in all nine symptoms scales of SCL-90 and lower FCI scores. Stepwise regression models
proved that the gender effect on FCI could be effectively explained through the significant effect
of de…