If your kids are no longer surprised by the way baking soda and vinegar react, they’ll be charmed with the way a new ingredient can reveal secret messages thanks to acids and bases: cranberry sauce!

First, I stirred 3 teaspoons baking soda into a little warm water in a paper cup. We used q-tips to write out “secret codes” on thick white paper. Travis wrote down the names of favorite characters, Veronika scribbled, and I made a few drawings that I knew would work well for the big reveal, like boats and suns.

You can let the messages dry naturally, but hair dryers are so much more fun of course. Travis jumped at the chance to set the dryer to low and wave over the pictures.

For the reveal, I emptied a jar of cranberry sauce into a container and smoothed it into an even layer. Press your pictures firmly into the cranberry sauce (but don’t submerge), then lift up to see what appears!

Simply wipe off any excess cranberry sauce and the pictures are ready.

Kids can end the activity here, or add color with colored pencils for a pretty final result if you want to add in a little arts & crafts.