Writing Secret Messages

Looking for a cool science activity for you and your kids?  Try writing secret messages using lemon juice!  The setup is very easy.  Pour a small bowl of lemon juice, dip a Q-tip into the juice, and use the Q-tip to write a message on a standard piece of white paper.  Let the lemon juice dry.  When it dries you'll be able to tell something is there because the paper will crinkle but you won't be able to read it.

Here's my 6 year old's secret message.  Again, you can tell something is there, but it's really hard to tell what it says.  My 3 year old created a secret message too, but it was basically one big blob of lemon juice!  :-)

Once the paper is dry, heat it up.  I tried using a candle to start, but that didn't work very well.  Next I used the stove burner, but you have to be very careful to not light the paper on fire!  This activity definitely requires parental supervision.  After heating the paper, here is what we found.

Pretty cool!  See the oven mitt on my hand?  Yep, it got a bit warm holding the paper above the burner!