My kids were given a pre made kit of bath bomb making. They really enjoyed the process and the science behind how a bath bomb works.
The set of instructions come in side the packaging, and are a great project for age 7 and above.
So if your stuck for a gift to give your kids, we can recommend this craft science kit, and it is fun for them to give a little bath bomb to their friends!!
You can buy bath bomb kits, here .
Once you have learnt the basics you could make more.