This is a perfect kind of problem that gets kids engaged with math in a deceptively clever way.
You’ll find these kinds of problems all over Facebook. Some online marketers even use them to hook an audience by the challenge of “98% fail this simple test.” Everyone wants to see if they are part of the 2%.
Here’s an important suggestion to make sure your students get bragging rights to this 2%.
When you pose this problem, look for the obvious mistake that most people make. Then add to the directions something like, “Can you find more than 30?” This steers them around quick glance answers of 16 or 24. They start to look at the figure more closely and discuss how in the world could there be more than 30?
You’ll probably notice that students who don’t easily engage with typical word problems will be very intrigued by this kind of problem. So when they discover the solution and can explain it to their peers, they get excited. Wow! They are the 2%! Their math confidence goes through the roof! Yay for them, and yay for you!!
Hey, have you heard about the Math Boot Camp?