This 8 question worksheet contains the formula to find compound interest along with 8 real life questions. I have used this worksheet with 8th and 9th graders and it really sparks their interest.
Kids, especially young teens, love to talk about money.
I have used it for several purposes:
1) to teach this specific formula
2) to help kids practice using formulas
3) to motivate kids to like math
4) homework assignment
5) substitute work (as long as it has been explained before hand.