지도서 · Part 8 · 9 / 11

Subtract across 10: two ways10을 넘는 뺄셈 — 두 가지 길

15 − 7 = 8. Ones first, or take from the ten.

Step 10워크북 15–16쪽 →고침 2026.11.12
한국어 요약

15 − 7처럼 10을 넘는 뺄셈(받아내림이 있는 뺄셈)을 두 가지 길로 보여 줘요. 하나는 빼는 수를 갈라 낱개를 먼저 빼서 꽉 찬 10을 만들고 나머지를 10에서 빼는 길, 다른 하나는 10에서 통째로 빼고 10에 남은 것과 그대로 있는 낱개를 함께 보는 길이에요. 풀기 전에 '답이 10보다 클까, 작을까?'를 먼저 묻고, 덧셈으로 답을 확인해요.

이 주제의 단어a full tenthe restonesstill here
이 주제 차례 (8)

The big idea핵심

When Lia takes away more than the ones, some must come from the ten. So the answer is less than 10. 15 − 7: 7 is more than the 5 ones. There are two good ways. Both use bonds to 10.

Way 1: take away to 10 first. Split 7 into 5 and 2. Take away the 5 ones: that leaves a full ten. Next, take away the rest from the ten: 10 − 2 = 8. Both pieces must be taken away — the rest is taken away, not added. The split depends on the ones: for 16 − 7, split 7 into 6 and 1.

Way 2: take from the ten. 16 − 9: 16 is one ten and 6 ones. Take 9 from the ten: 1 is left in the ten. The 6 ones are still here. So 1 and 6 are left: 16 − 9 = 7.

Both ways give the same answer. In the videos, Lia does 16 − 7 both ways: “Both ways start with sixteen. Both ways take away seven. So both ways leave nine!” Let her use the way she likes.

At school, way 2 is often written with an addition: 10 − 7 = 3, then 3 + 6 = 9. Here + only puts together the two groups that are left: 3 in the ten and the 6 ones that did not move. Nothing new comes in. In way 1, the second step is always take away.

761
Way 1 for 16 − 7: split 7 into 6 and 1
8910111213141516−6−1
Way 1: take away 6 to get to 10, next take away the rest
Way 2 for 16 − 7: 16 is one ten and 6 ones
Way 2: take 7 from the ten — 3 are left, the 6 ones are still here

Get ready준비물

  • Two ten frames — or draw two boxes, each 2 rows of 5
  • 20 counters, buttons or dried beans
  • A small strip of paper to cut into two pieces (the number you take away)

Teach it, step by step단계별 수업

YOU 부모가 할 말CHILD 아이가 할 만한 대답DO 손으로 할 일

More or less than 10?

DOPut 15 on two ten frames: a full ten and 5.
YOU“We take away 7. Is the answer more or less than 10?”
CHILDLess than 10.
YOU“How do you know?”
CHILD7 is more than 5. So some come from the ten.

Ask this before any working out. It is about the size of the answer, not the exact answer.

Way 1: ones first, then the rest

DOWrite 7 on a strip of paper. Cut it into two pieces: 5 and 2.
YOU“Take away the 5 ones first. What is left?”
CHILDA full ten.
YOU“Is the 7 all done?”
CHILDNo. The 2 is not done. 10 − 2 = 8.
YOU“How do you know 15 − 7 = 8?”
CHILD8 and 7 make 15.

Tick each piece of the strip when it is done. A piece with no tick is still to take away.

Way 2: take from the ten

DOPut 16 on two ten frames: a full ten and 6.
YOU“Take 9 from the full ten. How many are left in the ten?”
CHILD1.
YOU“What is still here?”
CHILDThe 6 ones. So 1 and 6 are left: 7.

Cover the 9 with your hand in one go, not one by one. If she says 1, point to the 6 ones: “Did they move?”

Two ways, one answer

YOU“Do 16 − 7 one way. Now do it the other way.”
CHILD9 both times!
YOU“Why is it the same?”
CHILDBoth ways start with 16. Both ways take away 7.

Do not say which way is “right”. Both are.

광고

Other ways to say it다른 표현

  • “Is the answer more or less than 10?”
  • “Take away the ones first.”
  • “That leaves a full ten.”
  • “Next, take away the rest.”
  • “Take it from the ten.”
  • “How many are left in the ten?”
  • “What is still here?”
  • “Don't forget the ones!”

Good questions to ask좋은 질문

  • “13 − 4: is the answer more or less than 10? How do you know?”

    Good answers

    “Less. 4 is more than the 3 ones, so some come from the ten.”

  • “14 − 3: is the answer more or less than 10?”

    Note

    More. 3 is less than the 4 ones, so the ten stays full: 11.

  • “Which way do you like for 11 − 6? Why?”

    Note

    Either way is fine. 11 − 6 = 5.

  • “How can you check 15 − 7 = 8?”

    Good answers

    “8 + 7 = 15.”

If Lia is stuck막힐 때

  • When

    She takes away to 10, then adds the rest: 15 − 7 → “12”.

    “Is the answer more or less than 10?” Some came from the ten, so it must be less than 10. Take away the rest: 10 − 2 = 8.

  • When

    She takes from the ten and forgets the ones: 16 − 9 → “1”.

    “What is still here?” Point to the 6 ones. They did not move. 1 and 6 are left: 7.

  • When

    She takes away to 10, then gives the rest as the answer: 15 − 7 → “2”.

    “2 is what you take away from the ten. What is left?” 10 − 2 = 8.

  • When

    She stops at 10: 15 − 7 → “10”.

    Point to the strip: the 5 is done, the 2 is still to take away.

Game놀이

Game · More or less?

You need: nothing at all, or two ten frames and 20 counters

  1. One player says a teen number and a number to take away: “17 take away 3.”
  2. The other player says “more than 10”, “less than 10” or “exactly 10” — no working out yet.
  3. Work it out together, one way or the other way. Were you right? Then swap.

Extra challenge더 도전

  • Missing numbers: 15 − □ = 8. 12 − □ = 3.
  • Which is more: 18 − 6 or 18 − 7? How do you know without working it out?
  • A bigger number: 23 − 6. Take away 3 to get to 20. Next, take away the rest: 20 − 3 = 17.
In the workbook

Two pages: take away to 10 first, then take from the ten and find what is still here.

워크북 15–16쪽 보기이 주제 인쇄

자주 묻는 질문

subtract across 10은 어떻게 하나요?

15 − 7이라면 7을 5와 2로 갈라요. 낱개 5를 먼저 빼서 꽉 찬 10을 만들고, 나머지 2를 10에서 빼요. 10 − 2 = 8이에요.

subtract from a 10은 무엇이 다른가요?

16 − 9라면 9를 10에서 한 번에 빼요. 10에 1이 남고 낱개 6은 그대로 있어서 1과 6, 7이 남아요. 학교 공책에는 10 − 9 = 1, 1 + 6 = 7처럼 덧셈으로 쓰기도 해요.

15 − 7을 12라고 하면요?

10까지 뺀 뒤 나머지 2를 빼지 않고 더한 실수예요. 낱개보다 많이 빼면 10에서도 빠지니 답은 10보다 작아요. 나머지도 빼면 8이에요.

광고