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# Start here!

Overview of this lesson

In this lesson we are going to develop the mathematics behind the subdivision operation. We used subdivision in the previous lesson to make smooth shapes like this:
To get there we must develop our understanding of weighted averages of three points.

Next we'll look at how weighted averages are used during the subdivision operation. This will tell the points where to go after we click average:
Weighted averages are used to define where points go after the average step

But if we aren't careful with the weights used in the averaging step we'll get funky behaviours like this:
By the end of this lesson you'll understand how computer modeling tools work underneath the hood. You'll be able to describe mathematically why those points move the way they do.

# What do I need to know before starting?

• You should be familiar with how to calculate the weighted average of two points. We covered this in the Environment modeling lesson here.
• You should have mastered grade 6 level algebra (this exercise should be easy for you)