Round Robin multiplication

On Tuesday night I was reading someone's blog (I can't remember who!) and they had linked to Sherrie from Middle School Math Rules and her round robin one step equation. I loved this idea!
I immediately adapted it for use in our classroom. It turns out it was perfect for revising algorithms for double digit by double digit multiplication.

The kids worked in threes with students using one colour for multiplying by ones, one colour for multiplying by tens and one colour for adding together. At the end they used rounding to check for reasonableness.

I extended some of my girls by asking them to try 532 x 47 after they finished four or five examples of the 2 digit by 2 digit. A great introduction to next week's lesson on the same!

Some of my students mastered double by double digit multiplication a few weeks before the holidays so I gave them a challenge: three digit by three digit. Two girls worked together to figure out how to tackle the problem on the left. We talked about the strategies they used then I asked them to write an explanation which you can see here:

At first we weren't sure if there were one zero or two zeros so we thought there might be a pattern like if you multiply by thousands there will be three zeros.

I ♥ that the girls figured this out! We then talked a little bit about why there is a pattern but I don't think they've really made the connection to place value yet.

What a valuable activity! It gave support, success and confidence to those students who have not yet mastered the skill; it provided revision for the students who mostly remember how to solve these problems but not yet consistently; and it offered scope to extend the students with a great understanding already. Thank you Sherrie for sharing!