The Moonjar Moneybox concept is on the money.  Save, share & spend is simple enough for even a young child to grasp.  At the same time there are many teachable momemnts.  The passbook and educational information is interesting and not overwhelming, according to my 8 year old son's response.  Finally, the product is sturdy, yet accessible.  We've had other "piggy banks" that are too easy or not easy enough to get into (i.e. transferring accumulated funds to the bank, etc.).  We are really growing with this product, and I will be purchasing more as gifts.