My girls really loved this craft. I think my youngest is a bit of pyromaniac. She kept saying "I need more fire!"
Start by drawing a heart on a piece of construction paper.
Next, carefully hold the crayon in the flame for a split second. (Supervision is required during this step, I held the crayon and then passed it to my girls.) You want it to be softened but not so much that it drips onto the candle. Run the crayon along the paper.
You can use different shades of red, pinks and whites. For the prettiest effect make sure the outline is covered.
Lastly, cut out the heart. You can then paste it onto a contrasting colored paper or lace or whatever you want to experiment with. Be creative and have fun!