Fraction Classroom · 2.0.0 · Student pages
Trade one whole before subtracting
Exchange one whole for fractional parts, keep the total value, and explain mixed-number subtraction with same denominators.
Anonymous group code: __________ Date: __________
Quick diagnosis
Try all three. Explain with words, a sketch, or objects.
d2. A student computes 2 1/5 − 3/5 as 2 2/5 by reversing 1 − 3. Explain the problem.
d3. Which is equal to 3: 2 4/4 or 2 3/4? Explain.
Worked examples
Study the example that matches the difficulty. Keep the other for a second session.
w1. Find 3 1/4 − 1 3/4 by trading one whole.
- Represent 3 1/4 as three wholes and one fourth.
- Trade one whole for 4/4: 3 1/4 = 2 5/4.
- Remove one whole and three fourths: 2 5/4 − 1 3/4 = 1 2/4.
- Check by adding 1 2/4 and 1 3/4 to recover 3 1/4.
Worked example: 1 1/2, or 1 2/4.
w2. Find 2 − 5/6 using a whole-number starting amount.
- Write 2 as two whole strips.
- Trade one whole for six sixths: 2 = 1 6/6.
- Remove five of the six sixths.
- One whole and one sixth remain; 1 1/6 + 5/6 = 2.
Worked example: 1 1/6.
Practice
For a short session, choose three tasks. Use the others for a second try or follow-up.
p1. Rewrite 4 2/5 using exactly three wholes.
p2. Calculate 2 1/3 − 2/3. Show the trade.
p3. Find 3 − 7/8 and check by addition.
p4. Does 4 5/6 − 2 1/6 need a trade? Find the difference.
p5. A student writes 5 1/4 = 4 4/4. Locate the lost amount and repair the equality.
p6. Complete __ + 1 5/8 = 3 1/8. Use subtraction, then check.
Transfer check
Try one independently. Save the other for a later check.