How can I do well in summer school?

I had to take first semester geometry over again second semester and I passed but I regret that I didn't get at least a B in that class since it was so easy. Now, second semester is a bit tougher but it's still manageable. The problem is, in summer school we learn 3-4 sections in a day and have a test or quiz every few days and it's really stressful. I want a good grade in that class and I'm sick of getting C's in math. Today we had a test and I think I did good on it except I forgot how to do 2-3 of the problems and then I looked back at my notes when the test was over and I knew how to do it. I also have been going to bed late (like tonight). I just hate it. I want to sleep in, not be in school. I know it's my fault but I just need to know how to do better in math. How can I commit 3 sections a day to memory? Also, where can I get some cheap calculators? Someone stole mine at the end of second semster.