Answer Key: Multiplication and Fair Shares
How to use this key
Answers are grouped by section and question number, with the full steps. Accept any correct method that reaches the right answer — drawing dots, skip-counting, repeated addition, or a known fact are all fine at Grade 3. A basic calculator is allowed, so grade the reasoning and the drawing/steps, not just the final number. Watch-for notes flag common misconceptions. Estimated grading time: ~3–5 min per packet.
Start Warm-Up ~1 min
1 Skip-count by 5: 5, 10, 15, ___, ___.
2 How many in all — 3 groups of 4 dots (Figure 1).
Build Study the Math ~1 min
3 Find 5 × 2 (5 groups of 2).
Apply Use What You Know ~2–3 min
4 Equal groups: 5 bags, 4 apples each.
5 Array match (Figure 3): 2 rows of 6.
6 Fair share: 15 crayons shared among 3 friends.
7 Find and fix the mistake (Figure 4): 4, 3, 4 dots.
Correct count: add the groups: 4 + 3 + 4 = 11 dots in all.
Full credit requires (1) naming that the groups are not equal (Group 2 has 3, not 4) and (2) the correct total, 11. Alternate: a student may fix it by saying "if it were really equal groups, add one more to Group 2 to make 3 × 4 = 12" — accept this if they clearly explain the groups were unequal.
Explain Tell How You Know (Q8) ~1–2 min
8 Explain the fair share of 15 crayons among 3 friends.
Explanation scoring rubric (3 points)
| Score | Answer | Picture or numbers | Why (reasoning) |
|---|---|---|---|
| 3 | Correct: 5 each. | Shows 3 equal groups of 5, or 15 ÷ 3 = 5 (or 3 × 5 = 15). | Clearly says it is fair because every group has the same number. |
| 2 | Correct: 5 each. | Some picture or numbers shown, or a small slip. | Reasoning present but incomplete (e.g., "everyone gets 5" without saying why that is fair). |
| 1 | Answer attempted, may be wrong. | Little or no picture/numbers. | Weak or missing reasoning. |
| 0 | No/incorrect answer. | No work. | No reasoning. |
Close ACE ~1 min
ACE Articulate / Connect / Extend.
Connect: items where students multiplied include Q3, Q4, and Q5 (and the check in Q6/Q8). Any correctly named item earns credit.
Extend: any correct equal-groups multiplication fact not in the packet — e.g., 2 × 5 = 10, 3 × 3 = 9, 4 × 2 = 8, 2 × 6 = 12. Check the fact is true and uses equal groups.
Challenge Early Finisher (optional)
EF Draw 6 × 2, then the same as a 2 × 6 array.
Watch Common misconceptions
- Adding instead of multiplying. In Q4, a student may write 5 + 4 = 9 instead of 5 × 4 = 20. Remind them "5 bags of 4" means 4 counted 5 times, not 5 + 4. Drawing the 5 bags with 4 apples each makes it clear.
- Unequal groups (the Q7 error). Students see three ovals and multiply 3 × 4 without checking that each group truly holds 4. You can only multiply when the groups are equal; when they are not (4, 3, 4), you must add: 4 + 3 + 4 = 11.
- Mixing up × and ÷. In the fair-share problem (Q6), some students multiply 15 × 3 instead of dividing 15 ÷ 3. Anchor the words: "share equally" and "each gets" signal division. Check by multiplying back: 3 × 5 = 15.
- Rows vs. columns. In Q5 a student may call it "6 rows of 2." The product (12) is still correct, but coach the labels: rows go across, and here there are 2 rows with 6 in each.
- Skip-counting by 1. In Q1, watch for 16, 17 instead of 20, 25 — the student counted by 1, not by 5.
Teacher follow-up based on likely errors
If many students miss Q7, do a quick picture of three equal groups next to three unequal groups so they see multiplication needs equal groups. If Q4 shows 5 + 4 = 9, draw the bags of apples and count. If Q6 shows multiplying instead of dividing, deal out counters (or drawn dots) into 3 groups to model fair sharing, then check with 3 × 5 = 15. The Q8 explanations show who understands why a share is fair — a good warm-up for next class. The separate student packet has all the models printed; this key is for the teacher only.