I was looking for an interesting way to teach our girls about the phases of the moon when I came across this activity that uses Oreo cookies. Like the write on Sciencebob.com, “I’ve always been a fan of science activities that you can eat.” Sadly you can’t use Girl Guide sandwich cookies as you really need the contrast between the white icing and the dark cookie. We split the girls up into groups of 4. Each girl got two cookies (a reasonable serving size). We also gave them napkins to work on, sticks to scrap icing off with and a copy of the PDF activity sheet from Sciencebob.