One of the things I'll be doing today is playing at the site SolveMe Mobiles. Your progress can be saved and you can create your own puzzles. Here is puzzle #15 from the explorer collection and puzzle #71 from the puzzler collection.
We know that to keep the mobile balanced what is on the left must equal what is on the right. As a matter of fact, if you click on the horizontal bars and drag them, you get systems of equations. And then if you "pull down" with your mouse on the right heart, it subtracts one heart from both sides of the equation.
Thanks to Kevin Smith for reminding me about this resource at his Global Math Department session last night. His session was called "Gamify the Math Classroom" and you can view the video of the webinar here. Note that if you are not a member of the Global Math Department, you will be prompted to set up a free account. However, when you do that you'll be able to see many of the other wonderful free webinars that have been recorded over the past several years. I serve as host for many GMD sessions and we are always looking for quality presenters. If you are interested in presenting, send me an email at firstname.lastname@example.org.