A focused Grade 3 learning session for Multiplying by Multiples of 10 using visual models, worked examples, strategy guidance, and a short mastery check.
Student goal: I can multiply a one-digit number by a multiple of 10.
Multiplying by Multiples of 10 means understanding equal groups, arrays, and repeated addition as multiplication.
Question: How many stars are there? Skip count by \(10\)s to find the total.
Why it works: Skip count by \(10\)s: \(10, 20, 30\). There are \(3\) groups of \(10\) stars, so \(3\times10=30\) stars total.
Answer: \(30\)
Question: Sam has \(8\) groups of \(10\) stickers. How many stickers does Sam have in total?
| Tens | Ones |
|---|---|
| 08 | 00 |
Answer: \(80\)
Question: Look at this number bond. What value should replace the question mark?
Answer: \(10\); multiply
Question: Noah buys \(7\) packs of pencils. Each pack has \(10\) pencils. How many pencils does Noah buy?
Why it works: \(7\) packs of \(10\) pencils \(= 7 \times 10 = 70\) pencils.
Answer: \(70\)
Multiplying by Multiples of 10 becomes easier when students connect the question to a model, use clear steps, and explain why the answer fits.
Equal groups make multiplication make sense.
Use scratch paper. The explanation matters more than simply seeing whether the choice is correct.
What is \(6\times40\)? Show your thinking: \(6\times40 = 6\times(4\times10) = (6\times4)\times10\).
Answer C: \(240\)
Multiply \(6\times4=24\), then multiply by \(10\) to get \(240\): \(6\times40 = 24\times10 = 240\). You decompose \(40\) as \(4\times10\), then use the associative property.
How many stars are there? Skip count by \(10\)s to find the total.
Answer D: \(30\)
Skip count by \(10\)s: \(10, 20, 30\). There are \(3\) groups of \(10\) stars, so \(3\times10=30\) stars total.
Which repeated addition matches \(5\times10\)?
Answer C: \(10+10+10+10+10\)
\(5\times10\) means \(5\) groups of \(10\), which is the same as adding \(10\) five times: \(10+10+10+10+10=50\). This shows that multiplication is repeated addition.
Quinn calculated \(7\times30\) and got \(710\). What error did Quinn make?
Answer D: Quinn wrote down the digits \(7\) and \(30\) instead of multiplying them.
\(7\times30=210\) (multiply \(7\times3=21\), then multiply by \(10\)). Quinn wrote \(7\) and \(30\) together as \(730\) instead. The correct answer is \(210\).
This array has \(2\) rows. Each row has \(50\) squares. How many squares in total?
Answer C: \(100\)
\(2\) rows of \(50\) squares \(= 2\times50=100\) squares. Multiply \(2\times5=10\), then multiply by \(10\) to get \(100\).
Which shows why \(4\times20\) equals \(80\)?
Answer D: \((4\times2) \times 10 = 8 \times 10 = 80\)
\(4\times20 = 4\times(2\times10) = (4\times2)\times10 = 8\times10 = 80\). This uses associative property: you break \(20\) into \(2\times10\), multiply the single digits first, then multiply by \(10\).
Sam has \(8\) groups of \(10\) stickers. How many stickers does Sam have in total?
Answer D: \(80\)
\(8\) groups of \(10 = 8 \times 10 = 80\) stickers. The place-value chart shows 8 tens and 0 ones, which equals 80.
What is \(9\times30\)?
Answer C: \(270\)
Multiply \(9\times3=27\), then multiply by \(10\): \(9\times30=270\). Add exactly one zero—not zero zeros, and not two zeros.
Look at this number bond. What value should replace the question mark?
Answer D: \(10\); multiply
\(60 = 6 \times 10\). The number bond shows that \(60\) can be decomposed into \(6\) and another factor; that factor is \(10\). You multiply \(6\times10\) to get \(60\).
Ava makes \(5\) sets of picture cards. Each set has \(20\) cards. How many cards does Ava make?
Answer C: \(100\)
\(5\) sets of \(20\) cards \(= 5 \times 20 = 100\) cards. Multiply \(5\times2=10\), then add one zero.
Look at this pattern: \(3\times10=30\), \(3\times20=60\), \(3\times30=90\). Using the pattern, what is \(3\times70\)?
Answer C: \(210\)
The pattern shows: each time we multiply by a multiple of 10 that is 10 more, the product increases by 30. From \(3\times60=180\) to \(3\times70\), we add another 30 to get \(210\). Or: \(3\times7=21\), then multiply by \(10\) to get \(210\).
