The objective of including lessons based on different subjects in the textbook at the upper primary level is—

At the upper primary level, textbooks include lessons based on diverse subjects (science, social studies, environment, etc.) primarily to familiarize children with different registers, styles, and varieties of language usage (प्रयुक्तियाँ). Each subject has its own terminology, sentence patterns, and discourse style, which exposes learners to the rich variety of language. This helps develop register awareness — that language varies according to subject matter, purpose, and context. The language textbook is not meant to teach those subjects or simplify them; it uses them as vehicles to expose children to varied linguistic forms. This aligns with NCF 2005's view of language across the curriculum.