Wednesday
Wednesday: Fraction times a fraction
Donnie walks slowly around a square garden plot near the creek.
"Bennie planted 3/4 of this plot," he says.
"And clover grows on 2/3 of the planted part."
"What fraction of the whole plot has clover?"
Bennie draws the plot in the dirt with a stick.
"We want 2/3 of 3/4," he says. "Of means times, so we multiply 2/3 × 3/4."
Donnie watches carefully, his ears twitching.
Learn it: multiply the tops and the bottoms
Split the plot into 4 equal columns, and shade 3 of them. That is 3/4.
Now split the plot into 3 equal rows. Clover covers 2 of the 3 rows in the shaded part.
The plot now has 3 × 4 = 12 small parts.
Clover covers 2 × 3 = 6 of them.
So 2/3 × 3/4 = 6/12, which is 1/2.
The rule: multiply the numerators, and multiply the denominators.
(a/b) × (c/d) = (a × c)/(b × d). For example, 1/2 × 3/5 = 3/10.
- Read the question.
- Tap your answer.
- Read the question.
- Tap your answer.
- Read the question.
- Tap your answer.
- Find each product: 1/2 × 1/2, 2/3 × 3/4, 1/2 × 3/5 and 5/6 × 3/4.
- Put the products from least to greatest.
| Sentence | True or false? |
|---|---|
| 2/3 × 3/4 = 1/2 | ? |
| 1/2 × 1/2 = 1 | ? |
| 1/3 × 3/5 = 3/15 | ? |
| 2/5 × 2/3 = 4/8 | ? |
Unfold it, then fold it into 3 equal rows.
Shade 2 of the rows again, across the shaded columns, in a new color.
Count the parts with both colors. What fraction of the paper is that?
Wonderful! Tomorrow Chris tells a story about a clover bed.