Here's a nice PDF worksheet on comparatives and superlatives which covers most essential points on them. It's excellent for revision lessons as a final test to check student's knowledge of comparatives and superlatives. The questions are based on some common mistakes and also check whether the meaning in comparatives structures is fully grasped or not.
This PDF print-out set includes a QR code answer key. It'll be a helpful tool if you don't have sufficient time and give this worksheet as a homework assignment. There are also some precise feedback notes are provided for your convenience at class time. You can ask for a rationale for each question to check student's understanding of the answer. Also, the feedback notes can be turned into Concept Checking Questions easily, which will help you conduct the lesson in English and make sure the grammar points are understood.
You can try out the online version here.