Our three and a half year old loves Math Tree and is getting a lot of use from it. I see the limitation to numbers ten or less as a strength of this app, not a weakness. There are plenty of apps to drill grade school children on addition. This one teaches familiarity with the digits zero through nine, and the concepts of addition and subtraction, in a solid and intuitive way. It is perfect for children who can recognize the digits but are a little hazy on exactly what they represent, and who are just getting started with arithmetic.
federationoffear about The Math Tree, v1.0