Making a charity your final beneficiary

I want to leave part of my estate to my favorite charity, but rather than give individual assets or specify an amount of cash, I'd like it to receive whatever is left over after my kids get their inheritances. Can I do that?

Sure. It's called a residuary bequest. Your attorney can include language in your will saying that after all other bequests, taxes, and expenses have been paid you want the balance ("residue" is the legal term) of your estate to go to your specified charity. Verify its legal name so there's no potential for confusion with another group.