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Kitchen 3-5 / Week 06 / Tuesday
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Week 06 · Fractions in the Kitchen

Tuesday

Adding fractions of a cup
// Halve it, double it, add it up
⏱ about 15 min

Tuesday: Adding Fractions of a Cup

Bennie scoops 1/3 cup of oats into a bowl. Then he scoops 1/3 cup more.

"How much is in the bowl now?" he wonders.

Ferris points at the scoop. "What do you notice about the bottom numbers?"

Riley holds up two fingers. "Here is a hint," he says. "Count the thirds."

Same bottom number, add the tops

When fractions have the same bottom number, add the top numbers.

The bottom number stays the same.

1/3 plus 1/3 is 2/3. Two thirds of a cup.

1/4 plus 2/4 is 3/4. Three fourths of a cup.

ScoopsAdd the topsTotal
1/3 + 1/31 + 1 = 22/3 cup
1/4 + 1/4 + 1/41 + 1 + 1 = 33/4 cup
2/4 + 2/42 + 2 = 44/4 = 1 cup
Bennie adds 1/4 cup of raisins, then 2/4 cup more. How many fourths in all?
Lizzy pours 2/3 cup of water, then 1/3 cup. How many thirds in all?
3/3 cup is the same as how many whole cups?

Taking some away

Subtracting works the same way. Subtract the top numbers.

You have 3/4 cup of oats. You use 1/4 cup. Now you have 2/4 cup.

ADD OR SUBTRACT
  • Read the question.
  • Tap your answer.
1/3 cup plus 1/3 cup is what?
You have 3/4 cup. You use 2/4 cup. How much is left?
1/2 cup plus 1/2 cup is what?
StatementTrue or false?
1/4 plus 1/4 is 2/4.?
1/3 plus 1/3 is 2/6.?
4/4 cup is one whole cup.?
WHY THIS EXERCISEThe bottom number tells the size of each part, so it does not change.
Ferris adds 1/4 cup of sugar and 1/4 cup more. How many fourths? Type a number.
WHY THIS EXERCISETwo fourths, which is the same as one half.
For a grown-up
Let your child practice with dry rice and real measuring cups.
This day has no cooking. No heat and nothing sharp.
On paper, draw a cup split into 3 equal parts. Shade 2 parts. Write 1/3 + 1/3 = 2/3.

Fraction adder! Tomorrow is Kitchen Lab. You will prove it with real scoops.

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