Don't give your kids an allowance just because you received one. You might not want to give them one at all. I received an allowance as a kid. I can't remember how much it was and can't say that it created any great financial habits.
I got an allowance mostly because my parents got allowances when they were kids. But is tradition a good reason to give your kids money? There might be some good reasons for NOT giving your kids an allowance.
Should money even be used as a reward? Giving your kids money as a reward establishes the mentality that you only need to do things if you're getting paid.
There are better rewards than giving a child an allowance. Let them pick the family outing for the week, or just tell them how proud you are of their accomplishment.