I thought I should complete my latest post, making sense of adding in column (here), with a quick post on using Base Ten blocks to make sense of subtracting in column. My daughter is not there yet, but your child may be.
The picture above presents a concrete illustration of 43 – 15. It is quite helpful for kids to visualize that, when subtracting 15 to 43, they trade a Ten from the Ten column into Ones. Then, they can subtract 5 Ones to 13 Ones, 1 Ten to 3 Tens, and end up with 2 Tens and 8 Ones i.e. 28.
I just spent the morning in my son’s classroom. He is 4 and attends a Montessori school. Their approach to teaching math is amazing. Indeed, using concrete objects, little 4-5 years old kiddos solve 4-digits addition without even thinking about it. I should write a special post on the Montessori approach to Math. Quite inspiring, indeed.