Tuesday, April 16, 2013

4.NF.B.4 Multiplying Fractions with Snap Cubes

Multiply a Fraction times a Whole Number

Mariana uses snap cubes to find 3/7 of 14. To do this, she counts out 14 cubes and makes 7 equal groups. Then she combines 3 of these equal groups to find that 6 is 3/7 of 14.  She can see  
2 + 2 + 2 or 3 groups of 2 to determine this.

Maribel also shows how she constructed the same. This makes it visual and concrete for my bilingual students to see that 3/7 of 14 is 6, and 4/7 of 14 is 8.

The children really enjoy this activity because it made sense to them!

 Rigoberto shows 3 of 4 equal groups of 12. His answer is 3 + 3 + 3 or 3 groups of 3. Therefore, he can see that 3/4 of 12 equals 9.

Mariana records her work on her paper. She proves her answers by drawing pictures of the blocks and circling the number of groups to show her solution.

5/6 of 12 = 10, because she counts out 12 cubes and makes 6 equal groups with them. Then she circles 5 of the 6 equal groups.
Esmeralda also uses the same method to record and show her work. However, she takes another step and shows how she simplified her answers by dividing out common factors. (Careful! The drawing for number 6 doesn't match your answer.)

Esmeralda knows that n/n = 1, so common factors can be factored out in each problem to simplify the answer.

Jessi constructs 2/9 of 18 to prove that his answer is 4.  Again, he counts out 18 cubes, divides them into 9 equal groups, and takes 2 of those groups to find the answer of 4 cubes.

The children made a lot of connections today!  :)

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