equivalent fractions or “half of one, six twelfths of the other”
Post on 01-Apr-2015
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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!
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