Space and Geometry – 2D

Identifying polygons

Maths Reference Mat

Fraction

Let's break the hexagon into 6 equal pieces:

What if we just had one of the pieces?

That would be 1 piece out of 6 pieces. Right?

Here's how we write it:

We read this like "one sixth."
Let's do some more counting!

.....

How much of this hexagon is red?

5 pieces are red... out of 6 total pieces...

So, of the hexagon is red.

How much is blue?

1 blue piece... out of 6...

of the hexagon is blue.

Division

Let's see what's really going on when we divide one number into another number.

We start with 6 triangles:

We want to see how many chunks of 3 we can make out of 6 things!
We can divide 6 things into 2 chunks of 3.

---

Now, let's see how many times 2 will go into 6.

Start with 6 squares:

We want to see how many chunks of 2 we can make out of 6 things!
We can divide 6 things into 3 chunks of 2.

Multiplication

Let's see what's really going on when we multiply two numbers.

This means that you have two groups of 3!

Put the two groups together...  How many triangles do you have?

Count them...  One, two, three, four, five, six!
So, our answer is:

---

Let's do another one!  This one has the numbers switched around.

This means that you have three groups of 2!

Put the three groups together...  How many squares do you have?

Count them...  One, two, three, four, five, six!
So, our answer is:

Hey, that's the same answer we got with 2 x 3!  But, we put the six together a different way.  Look at them both again to see the difference!

Subtraction (Two Digit Value)

For this lesson, we'll be working with easy numbers just to get you used to how this stuff works.
We're going to work with everything stacked because this is what you'll always do with bigger numbers.
We're going to work backwards, just like we did with addition! 
I'm going to have you subtract the ones first... then the tens.  Like addition, you'll have to do it this way when the numbers get harder.
Let's jump in!

Stack them and line everything up:

Subtract down the stripes...  Do the ones first, then the tens:

Subtraction

 This is the very beginning of understanding how subtraction works.
Let's look at this set:

Count how many triangles
are in this set...  There are 5!

Now, take two triangles away...

Count how many triangles are left in the set...  There are 3 left!

Addition

This is the very beginning of understanding how addition works.

Let's look at two sets:

Set A	Set B
Count how many triangles are in Set A... There are 2!	Count how many triangles are in Set B... There are 3!

Now, put the sets together into one big set:

Count how many triangles are in this set...There are 5!