I saw this idea on Pinterest and wanted to try it. We made these at N2's Valentine's Day party at school as well.
Cut a heart shape out of a coffee filter. Have your child color on the heart. It's best to use a lot of color but not color in the entire heart. Scribbling is actually the way to go. Noah would NOT scribble though so his hearts don't look too tie dyed. You don't want to color all one color in the same area. You want to scribble all around.