What is it?
The start of the year is often the time you want to focus on developing and consolidating students’ key number skills, such as long multiplication, but this tends to be a little boring. With this puzzle, you get all the engagement that comes from a good challenge, but safe in the knowledge that students’ attention is focussed on the maths. It requires students to use logical thinking, together with their knowledge of factors and multiples. And they can always check their answer by carrying out the original multiplication.
How can it be used?
This is one of those activities that essentially runs itself. I would be tempted to start the lesson with an Example-Problem Pair on long multiplication. That is, I would model how to answer a question, and then ask students to complete a similar one on their own. If any students were struggling at this stage and felt they needed more practice, then they could do (or at least start on) the first activity. But for other students, the challenge of the second activity awaits them. Upon completion, they could also create their own challenges for each other.
Thanks so much for sharing!