In part one of how to teach multiplication, we discussed introducing multi-digit multiplication using base-10 blocks and moving students from concrete strategies to pictorial, and then to abstract. It is crucial to make connections along the way! Keeping that theme going we are moving to expanded and standard algorithm.
Since the last strategy we focused on was area model (or both method) we are going to start with that and connected it to partial products, also known as expanded algorithm. Demonstrate both side by side and have students discuss what is the same and what is different between the two strategies. Want to see it in action? Watch here.
I don’t always have students circle the different place values once we start working more of these out. I think it gets pretty messy that way…but I do this during my first few demonstrations of the strategy. Same thing with writing on the side what was multiplied. Not something I have students do forever, just something we do for now so that students know where each number came from.
Last, but certainly not least, we are going to take what we’ve learned and connect it to standard algorithm. Again, showing this to students side by side and having them make connections. Watch this video to see it in action.
Side note…I know standard algorithm isn’t necessarily the normal or regular way to do multiplication (that’s why it’s in quotations). I always just tell students this is the way their parents learned to multiply…and it’s probably the only way their parents know to multiply. Now they seen how you can use so many different strategies to get all the same answer! So they must be smarter than their parents 😉 They already think that…might as well give them a reason!
You can grab the FREE connecting expanded algorithm to standard algorithm sheet by clicking the link below.
Multiplying 1 digit expanded and standard
Free Printable Manipulatives are from my good friend and mathematical genius – Brittany from Mix and Math. You can grab them here.
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