The recipe called for 3/4 of a cup of breadcrumbs, so I found myself mentally halving this fraction, then thinking about how I mentally halved the fraction, then wondering how others may mentally halve the fraction. So I took to Facebook to ask how others would do this:
For such a seemingly straightforward problem, there was a wide variety of answers. Here are some of them:
- Change it to eighths
- I know that 1/2 of 1/4 is 1/8 and I need 3 of them, so 3/8.
- Convert to a decimal, .75 and then find half of that. 37 + 37 = 74, so half of .75 must be .375 - 3/4 means 3 out of 4 circles shaded. So split all 4 circles into 2 parts, so you have 6 shaded parts out of 8 parts. 1/2 of 6 is 3, so 3/8.
- Just double the denominator = 3/8
- Convert to decimal 1st.
- 4 * 2 = 8 3/8
- I split it into 1/4 and 1/4, then half of a fourth and add together as 8ths, so 2/8 + 1/8= 3/8
- Multiply denominator by 2 and simplify if necessary Funny story I did it today with pancake mix finding half of 2/3 🤦♂️, but hey it worked
- Ask Siri…or Alexa
- Equivalent fraction to make the numerator even, then halve it.
- Multiply 4x2
- I know I 3 parts out of four, it’s 3 quarter. It’s 0.75
- Convert it eighths first.
- Divide it in half
- Multiply by 1/2
- Half of .75
- I split 3/4ths in half using a bar model and count the pieces of the half left out of the total new pieces to get 3/8ths
- Double the denominator
- 3/4 x 1/2 = 3/8
- Picturing it as pizza slices.
- Not the shortest way, but my tendency with fourths is to think in terms of quarters. If I had 3 quarters, split in two groups, then I would have $0.25 + $0.125 in each group… then I realized keeping it as a fraction would have been more efficient! So 3/4 of a pan of brownies, each 1/4 could be cut in half. Then half the 3/4 would be 3/8. I love helping students think through problems by relating the scenario to money, food, or time!
- Half of 3 is 1.5. denominator stays same
- Half of 3/4 is 1.5/4, double to get the numerator a whole number
- 1/4 + 1/8 for 3/8 - 1/2 of 3/4 means 1/2 x 3/4 which is 3/8
- 1/2 of 1/2=1/4, 1/2 of 1/4=1/8, 1/4=2/8, 1/2 of 3/4=3/8. It seems like a long way around, but I can visualize it almost instantly.
- Convert to 8ths by multiplying both numerator and denominator by 2.
- Convert to an equivalent fraction with an even numerator (6/8). Half of 6 is 3, so 3/8. That's what my brain does.
- Keep the numerator then multiply the denominator by 2. Multiply 3/4 by 1/2 is the same thing.
- Multiply denominator by 2
- Double the bottom. “Half of” multiply by 1/2… So to find half of any fraction, just double the denominator.
- If you can't half the top you double the bottom
- In the real world, I don’t…I just take the 3/4 measuring cup and fill it half way.
- Three one-fourths cut in half is 1.5 one-fourths, which is equivalent to 3 one-eighths.
- .5 x .75 = .375 /2 of 3/4 is 1.5/4 so 3/8
- If I'm dealing with measuring cups/spoons....I split in to 1/2 and 1/4....1/2 of a 1/2 is a fourth and a half of a fourth is an eighth.
- I visualized 1/4 and asked what’s 1/2 of 1/4. Then multiplied by 3 or write 1/8 three times and added to get 3/8.
- 6/8, 3/8
I love all these answers because they highlight just how differently we all approach math in equally valid ways. Some methods may take longer, some may not work for other people, but the variety of the answers is what math is all about. Just maybe not the Siri one.
"Each and every student is capable of doing math on their own and for their own reasons."
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