Equivalent Fractions

or

“Half of one,

Six twelfths of the other”

What is a fraction?

• A fraction is part of a whole that is made up of equal parts.

Part of a whole what?

• Well, it could be part of a whole object, like the proverbial pizza . . .

• Here is a whole pizza.

• And here is 1/8 of the pizza.

18• Here is 7/8 of the pizza because

there are 7 out of 8 slices left.

78

And here’s the person who ate it.

Was there something else?

• Yes, it could also be part of a whole group of items.

• Here is a group of cookies.

• We could say 1/5 of these cookies are chocolate chip. We could also say that 4/5 are Oreos.

• Oops, let’s make that 3/4 are Oreos.

15

45

34

So, what are equivalent fractions?

• Well, sometimes an object or a group of items can be divided differently, and fractions can name the same amount.

Say, what?

• Okay, try this. Let’s take a rectangle and divide it into 8 parts.

• Now, if we color 2 parts, we say that 2/8 of the rectangle are shaded.

28

I’m with you. What’s next?

• Now, let’s take that same rectangle and divide it into 16 parts.

• If we color 4 parts, we say that 4/1 of the rectangle are shaded.

416

So that means?

• So that means 2/8 is equivalent to 4/1 .

• And we write it this way:

=

28

416

416

28

Give us another example.

• Okay, how about:

=

39

13

39

13

How do you find equivalent fractions?

• You can multiply (or divide), but you must multiply (or divide) both the numerator AND denominator by the same number.

14 x3

x3

=3

12

25 x2

x2

=4

10

What about dividing?

• Here’s how.

420 ÷ 4

÷ 4

=15

414 ÷2

÷ 2

=27

What if you’re not sure?

• Here is how you can check to see if two fractions are equivalent.

• You can “cross-multiply.”

15

210

=

5 x 2 = 10

1 x 10 = 10

• Since both products are the same, these two fractions are equivalent.

How do you know if they’re not equivalent?

• Here is an example. You still “cross-multiply.”

23

45

=

3 x 4 = 12

2 x 5 = 10

• Since both products are NOT the same, these two fractions are NOT equivalent.

Now what?

• Let’s do some practice activities in the computer lab.

• Here’s an activity we will do.

• Open MY COMPUTER.

Here’s what!

• Go to the X DRIVE.

Then…

• Navigate to our class folder (Class Files 5th Grade Postman).

• Navigate to our class folder (Class Files 5th Grade Postman).

• Navigate to our class folder (Class Files 5th Grade Postman).

• Navigate to our class folder (Class Files 5th Grade Postman).

It will look something like this.

• Go to VIEW and add a header for your name. Save on the N DRIVE. Save every few minutes.

• Highlight all the cells you need to shade for the first fraction on the first table.

1

2

4

8=

• Right click on the highlighted cells and choose BORDERS AND SHADING…

• Make sure it says APPLY TO: CELL. Then choose a color. Click OK.

• Then, shade the second fraction on the second table.

1

2

4

8=

• Continue until you have completed all the examples. On some you will need to complete one or more of the fractions. Just click where the number goes, and type.

1

3

4=

• On the last one, you need to create your own tables. Go to TABLE on the menu bar. Drag down to INSERT. Drag across to TABLE.

• Choose the number of columns and rows you will need.

• Save and print when you are done.

• Are there any questions?

• I’ll give you the written directions in the lab.

• Let’s go!