If added after sentence 3, which sentence would most improve this conclusion?
This would cause less frustration for teachers because they would not have to plan a lesson to reteach a concept that the students should already know. Because students would not need to spend so much time reviewing previously covered material, they would then have more time to master new concepts. Spending time re-learning old material is something I always dreaded at the beginning of each new academic year because it was a waste of time. Students would not lose as much information because the breaks would not be long enough for them to forget everything they learned the previous year