You are about to erase your work on this activity. Are you sure you want to do this?
Updated Version Available
There is an updated version of this activity. If you update to the most recent version of this activity, then your current progress on this activity will be erased. Regardless, your record of completion will remain. How would you like to proceed?
Mathematical Expression Editor
For each of the following, perform the multiplication without writing anything down,
and without using a calculator or other tool. You can write down your answer so that
you don’t forget it!
(a)
(b)
(c)
As a group, illustrate your solutions to each problem using a picture. Your pictures
can include objects, number lines, or whatever else makes sense to you! Try using
different types of pictures for each problem.
As a group, illustrate your solutions to each problem using equations. Be sure to
place the equals sign only between things which are actually equal! Did you use any
properties of arithmetic in your equations? If so, what were they, and where did you
use them? Be as specific as you can.
Cade solves in the following way.
I’m going to split into and into . Now that I see the , I’m going to split that into .
So we take and multiply that by . Now times is , and multiplying that by gives me .
If I do I can start with which is . Now multiplying that by I get times which is
and which is so all together that’s . Adding the gives me and that’s my
answer.
Why does Cade’s strategy give us the correct answer? Draw pictures or write
equations to help you understand this strategy. Did Cade use any properties of
arithmetic in this strategy? Explain your thinking.