This simulation uses student-made pieces or the plastic pieces found in the KD Biographics kit you can buy from many of the biological supply companies. Since I have the kits, it only takes one period, but if the students are going to cut them out, it would probably take 2 class periods. If you like this lab activity, you would probably want to start with my "DNA Model with Paper" activity which uses the same pieces. This lab doubles the number of pieces they need, but it is just twice the same pieces used in the DNA model lab. So, for this lab, make two of the pieces pages for each group. I have students keep these in envelopes for later use.