So as I have posted about many, many times – I love Cognitively Guided Instruction for Math. The emphasis of CGI is building conceptual knowledge and a solid foundation of math skills.
Anyways..I wanted to share quick tip for double and triple-digit multiplication by single-digit. It’s the break apart method. (I do also use break apart for adding and subtracting).
For multiplication, students break apart the larger number (usually the 2-digit or 3-digit number). Then, they multiply those numbers by the single-digit number. Once they’ve multiplied each number they broke apart, they add up what they got and find their product.
For example, in 493, my student broke it into 400 + 90 + 3. Then, she multiplied 400 x 5 and got 2,000. She multiplied 90 x 5 and got 450. Last, she multiplied 3 x 15 and got 15. She added all those numbers together to come up with her product of 2,465.
This tip is helpful to students because they see where each number is and where it comes from. Instead of the old method of stacking, where it gets confusing what the value is of the number, break apart allows students to clearly see what is the hundreds, tens, etc.
Just a quick math tip for today! Hope everyone is having a great week!