I had to reteach phenotype and genotype (online there is a great website with powerpoint slides using Harry Potter). Students had to also review types of bacteria.
I also went over some misconceptions about bacteria - e.g. if you are sick and the doctore prescibes some antibiotics, all the bacteria will die.
Students loved the activity. All my classes got the chance to do the activity. What a blast for students and me! I enjoy watching my students learn and work independently and cooperatively.