Sunscreen Science

Following the lead of Sid the Science Kid, we decided to find out how sunscreen counteracts the effects of the sun.  C and R each had their own piece of dark construction paper.  They folded the paper in half, coated one side of the paper with sunscreen (we used spf 45), and placed the paper out in the sun for a few hours.

We talked about sunscreen and how it protects our skin.  C and R did not really know what would happen to the paper out in the sun until we started talking about why we use sunscreen.  I asked them to think about what might happen to their skin if they forgot a spot when applying sunscreen.  This made both of them decide that the part of the paper without sunscreen will change and the part of the paper with sunscreen will stay the same.  At first, they thought the part of the paper without sunscreen would get darker.  I think this reasoning makes sense because our skin gets darker out in the sun. After completing the experiment, we also noted that a very thin layer of sunscreen did not work as well as a thick layer of sunscreen.

Here is an after photo, you can see how dark the paper is around the SPF letters and how light the other side of the paper is after fading in the sun:

Maybe C and R will be more willing to apply their sunscreen now.  We'll see.

Today is not Sunday, but Ticia from Adventures in Mommydom is the host of Science Sunday.  We plan on linking up another experiment on Sunday, but in the meantime, check out her blog.