Hands-On Math Number Balance

I really like the levels of questions that come with this app. I would like to see another level. I teach middle school and we have to cover mean as a balance point. I would love to have a way of changing the numbers on the balance so that it balances on a number other than zero. For example, setting the balance point to 3 so that weights on 1 and 5 would make it balance evenly.

I was excited to share this with my students. The number balance is one of my favorite math tools. But the app isn't working for me. It won't go past level one. Every, other level does not load properly and then quits as soon as the screen is tapped. I deleted and reinstalled the app to no avail. Any suggestions? I'd really like to be able to use this.