As part of our Math warm-up last week, we looked a strategies that help us solve what I call "scale problems" (pictured below). These problems come up in a variety of situations in our math program and EQAO.
To solve simple problems such as the one pictured above, students can select from a variety of strategies. They can use mental math, count back from 20 to 12, or subtract 20-12. The last strategy we explored was this one. The idea of solving first 8+4=12 and then carrying that 12 over to the other side of the scale and using it to solve for the mystery number.
The totally unscripted, no-prep-whatsoever video below shows the tale end of a lesson from 2016. My hope is that students will watch it at home and solve the problem at the end. Parents, you too can create scale problems for your children at home. They're a great way to build number-sense!