found this on the net while surfing:
Here is a copy of the Periodic Table of Elements and an article on isotopes. AND an excellent and CONCISE bit about the idea of "half-life".
Suggestion: bribe/pay your kids to draw the Periodic Table by heart. Initially, pay them to draw it by copying it once a week. And after they get good at it, start them doing it from memory.
After they get that down, pay them to look up each element and write a one page essay on each one. By copying at first and then from memory.
No idea how much kids get as allowance these days, but instead of them "getting" an allowance, let them earn the money by learning the Periodic Table. There are 100 elements [102 actually and probably a few "exotics" as well and more if you include isotopes], but a penny each is one dollar. A nickel is $5. A dime each is $10. Really young kids would probably enjoy memorizing adult stuff.