I would like to recommend a system that we started using in February. I bought this kit for my eight year old daughter to help her keep track of her money. We have sat down together at least twice a month every month since then to "organize her money" as she says. She earns $5 every two weeks as a compensation for her chores at home - and occasionally she earns from other sources. The cash goes in her 'earn' envelope' until we document how she wants to split it for 'give', 'save' and 'spend' allotments. All that information gets tracked on the paper ledger.
We have tried many systems with our four kids over the years and this one really dovetails nicely with the YNAB ideology. Our kids are very aware of the family budget, YNAB and the YNAB app

. This simple paper-only system for kids is prepping my daughter for when she is ready for the software. Our sons are a little older [11,14,16] and keep track of their money on their own - but now they are envious of the special attention and system that little sister is using. ANYWAY; all that is to say I highly recommend this simple budget system for kids who are old enough to earn money and need to keep track of it.
Please check out:
http://www.sticktoitcharts.com/ [I asked the creater of this product if I could post about it on this forum before I wrote this - I have no affiliation with this company except as a customer - I receive nothing for my recommendation]