This study examined relative abstract nature of Biology, Chemistry and Physics offered at the senior secondary schools (SSS) in Ankpa education zone of Kogi State of Nigeria based on the analysis of classroom interactions. In each of the three comparable public schools used, the same class of Senior Secondary 2 (SS 2) or 11th grade students were each taught Biology, Chemistry and Physics. In each school, reproduction, chemical kinetics and refraction were taught in Biology, Chemistry and Physics respectively. The researchers personally took record of interactions during the 9 periods (taught by 9 science teachers) lasting for 35 minutes each using Flanders’ Interaction Analysis Categories (FIAC). Inter observer’s rater reliability was 0.69 using Scott’s Phi coefficient. Using a 10 by 10 matrix and percentage for final analysis, the extent of students’ participation in the lesson which its decreasing order was used to estimate the degree of the abstract nature or difficulty experienced in each subject was determined. The result revealed that the physical sciences were more abstract than the biological science with physics having the highest index. There was no close match between teachers’ level of motivation during the lessons and students’ participation except in Biology. Consequent upon these, it was recommended that chemistry and physics teachers should always ensure that there is a close match between cognitive ability of learners and cognitive demands of the subjects or lessons taught; that concrete teaching materials be used in the two more abstract subjects to reduce the formal reasoning or abstract requirements in the lessons to concrete demand levels, among others.