Adding & Subtracting
📋 What it is
To add or subtract fractions you need the SAME denominator; then add (or subtract) just the numerators.
🗣️ Coach says
You can only add things that are the same size. Fifths and thirds don’t stack — so first make the bottoms match, then add the tops and keep the bottom. The denominator says WHAT you’re counting; the numerator says HOW MANY.
🧠 Memory hook
Same bottom, then add the tops. The bottom just names the piece — it doesn’t add.
😂 Giggle
Why did the decimal point get promoted?
It knew how to move to the right place!
😲 Whoa!
This is the #1 fraction mistake in the world: adding the bottoms too. 1/2 + 1/2 is 1, not 2/4 — the denominator names the piece and stays put.
✅ Quick check: What is 1/4 + 2/4? And why does the bottom stay 4?
Say your answer out loud first — then reveal.
3/4 — you add the numerators (1+2=3) and keep the denominator, because you’re counting quarter-pieces and the piece size doesn’t change.
Adding like-sized parts adds their counts, not their size.
🪄 Trick question: Is 1/2 + 1/3 equal to 2/5?
Careful — think it through, then reveal.
No — you can’t add unlike bottoms; convert to sixths first: 3/6 + 2/6 = 5/6.
Adding numerators and denominators straight across is the classic error.
🧪 Try it! (2 minutes)
Add 1/3 + 1/6 by first re-cutting thirds into sixths (1/3 = 2/6), then adding. Draw it to see it works.