SUPPLEMENTARY MATERIAL Yale University: Science Education Outreach Program

III.E) Who Ate the Cookies?

Materials: Give each child 2 strips of paper long and wide enough to write a DNA sequence of about 15 base pairs. (cut 8x11 piece of paper in strips)

Activity: First tell a story. There were a plate of cookies on the table and an hour later they were gone with only a part of one cookie remaining. Let’s pretend that someone at this table ate the cookies. We want to determine who ate the cookies. It turns out that the person took a bite out of piece of cookie remaining and there was some saliva with cells left on the cookie. Remember last week when we extracted DNA after scraping the inside of your cheek. We decided to use the same procedure to extract DNA from the remaining piece of cookie. We then obtained the sequence for one of the genes from the DNA sample.

Ask the children to write on their strip of paper a random sequence of 15 bases and write the complementary sequence below it. Then ask them to write the exact same thing on the second piece of paper. Collect one of the papers, fold, and put in bag. Ask students to pass other piece of paper to their neighbor on the right or left. Pick one sequence out of the bag, read sequence and ask students to see if their sequence matches what is being read. Identify who ate the cookie in a joking manner.

Activity gets students to think about DNA sequence and the power in using DNA sequence for identification purposes.