Parent guide · Grade 1 Math · Unit 3

Lesson 3.4 Missing Numbers

Written for the parent. Read the Say this lines aloud as they are, or in your own words. Answers for you are marked Listen for.

At a glance

Time: 5 sessions of 20–25 minutes
Goal: Find the missing number in a number sentence.
You need: Pencil and crayons
Print: Worksheet A · Worksheet B · the lesson page

Steps

Warm-up
Do this: Ask these out loud. Your child answers out loud; no paper needed.
- Ask: “14 − 8” Listen for: 6
- Ask: “9 − 4” Listen for: 5
- Ask: “12 − 6” Listen for: 6
- Ask: “10 − 4” Listen for: 6
- Ask: “5 − 5” Listen for: 0
Teach the new idea
Say this: “In 8 + ___ = 13, ask what goes with 8 to make 13.”
Say this: “Check by putting your answer back into the sentence.”
Say this: “Unknown: the number we are looking for, shown by a blank.”
Show how
Show: Find the missing number: ___ + 2 = 10
Say this: “Think: what goes with 2 to make 10?”
Say this: “10 − 2 = 8”
Say this: “Check: 8 + 2 = 10”
Answer: 8
Show: Find the missing number: 4 − ___ = 1
Say this: “Think addition: 1 + ___ = 4”
Say this: “4 − 1 = 3”
Answer: 3
Practice together
Do this: Your child does these with you. Let them try first; help only after a real try.
Ask: Find the missing number: 1 + ___ = 5
Listen for: 4
If stuck: Think: what goes with 1 to make 5?
Ask: Find the missing number: 4 + ___ = 9
Listen for: 5
If stuck: Think: what goes with 4 to make 9?
Ask: Find the missing number: 1 + ___ = 1
Listen for: 0
If stuck: Think: what goes with 1 to make 1?
7 more practice items on the lesson page, and on Worksheet A and Worksheet B.
Watch for
- Writing the total (13) in the blank.
Game: Fact Family Houses
Draw a house with three numbers in the roof (like 6, 8, 14). Your child writes all four facts in the windows. Score a point for each correct fact.
Narration
Say this: “Tell me what you learned today. Show me with your hands or the counters if you like.”
Listen for: Find the missing number in a number sentence.
Daily habit
Count back from 20 by ones and by twos. Say the subtraction partners of 10 (10 − 1 = 9 …).

Spread over the week

5 sessions of 20–25 minutes. Stop while it is still going well.

Session 1. Warm-up, then teach the new idea (steps 1 and 2).
Session 2. Warm-up again, then show how with the examples.
Session 3. Practice together, then play the game.
Session 4. More practice on the worksheet, and the daily habit.
Session 5. Quick check: narration and a few practice items. Move on when it is mostly right.