My 6th-grade daughter is practicing basi
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My 6th-grade daughter is practicing basic integer arithmetic and made the exact same sign error across three problems:
1. 5 - (-3) = 2 (she calculated 5 - 3)
2. -4 - (-7) = -11 (she calculated -4 - 7)
3. 10 - (-8) = 2 (she calculated 10 - 8)
She keeps treating subtracting a negative as regular subtraction or ignoring the double negative flip.
Can you cluster these three missed problems into a single 5-line cause card (prompt, wrong, right, tag, cause) for our mistake notebook, and give an isomorphic test problem for her to solve without lecturing on general math theory?
Answer
I'll read the references and check the notebook state.
eading the family profile for timezone, then writing the card.
One card written (id `c8ed075162d404ac`) — all three misses folded under the same cause, not three separate cards.
**Five lines in the notebook:**
| line | content |
|---|---|
| Prompt | `5 - (-3) = ?` (representative of the three: `5-(-3)`, `-4-(-7)`, `10-(-8)`) |
| Wrong | `5 - 3 = 2` · `-4 - 7 = -11` · `10 - 8 = 2` |
| ight | `7 - (-4)` → rewrite as `7 + 4 = 11` |
| Tag | `integer-signs` |
| Cause | `A2` |
**Isomorphic problem for her to try right now (don't show the answer first):**
> `9 − (−6) = ?`
Let her work it from the rewrite step (`−(−6)` becomes `+6`), then check against the card's right line.
**Heads-up, not part of the card:** today's `due` list has 13 cards already waiting (fractions, borrowing, distribute-negative, order-of-operations, etc.). If you want to run her through the self-test on those before tonight, say the word and I'll start the cover→try→reveal flow; otherwise the card above is on the standard `[1, 3, 7, 14, 30]` ladder and will come back on its own.