We tried growing crystals last week! Here’s how we did it:
We added half a cup of baking soda to one cup of hot water and we stirred and stirred until the baking soda dissolved. Then we poured it into a cup with eggshells, added a little food colouring and waited a few days.
You have to look closely but there are crystals growing on the edges of the eggshells.
Note: If you try this at home, be sure to wash the eggshells thoroughly and completely remove the membrane otherwise the crystals may turn black.
Other options: Instead of baking soda, you can try salt or borax.