Erupting Ice Chalk

I found the erupting ice chalk recipe on Pinterest and thought it looked like fun.  I mixed one quarter cup of baking soda, one quarter cup of cornstarch, and one half cup of water and then scooped that into ice cube trays (both regular and the cute silicone design trays).  I added liquid watercolors to the trays, and then froze them.

 They looked very cool.

 I followed the directions for the chalk, and hosed the driveway just like the blogger that posted the recipe, but the chalk didn't really work for drawing/writing.  It just didn't show up.  I went back to the site and noticed that her driveway is light gray which is probably why the chalk worked for her and not for us.  That's okay though because the best thing about this chalk is definitely squirting vinegar onto the ice chalk pieces and watching it fizz.