I'm guessing that if you grew up around the same time I did, you experienced a similar progression. Master the 2 dimensional shapes and their measurements (perimeter and area) and then move on to the 3 dimensional shapes and their measurements. Throughout this process, at least in my elementary years, I'm fairly certain not a single elementary teacher I had in front of me had a degree (major or minor) in mathematics. So they did what they'd always done, show some pictures in books and talk about formulas and calculations. Once we made the leap to 3D though, my brain really struggled to "see" what was on the paper as taking up space - even with the paper nets we cut and taped into 3D objects. Do you suffer from the same affliction I do? I can't say that my parents didn't ask me to do this often enough or not, but I certainly needed some more practice! Don't shy away from letting your child do this kind of spatial thinking. Have them order containers s...