“Each new topic pushes out the last one”

Forgetting is not a fault in your students or your teaching. Memory keeps what gets used and drops what does not, and a curriculum taught in blocks stops each topic being used the day the next one starts. While you taught the unit, the material was in front of the class every lesson, so recall felt easy and the topic looked secure. That ease came from constant contact, and once the contact ends the forgetting starts, fastest in the first few weeks.

The pattern holds because the timetable rewards it. Moving on feels like progress, going back feels like time you cannot spare, and the end-of-unit test sits where memory peaks, so every topic looks learned just as it starts to fade. The cost shows up months later, in an exam, with little time left to act. Breaking the pattern does not mean reteaching whole units. The techniques below work in two ways: some keep old topics in circulation, with short bursts of recall in ordinary lessons and practice that mixes old questions with new, and some pin down what each topic must leave behind, so revisiting has a clear target.