Learn with Amar
Teaching video
A teaching recording for this chapter has not been published yet. Start with the worked example below and explore the related animations where available.
Grade 1 chapters and video availability01 · Read and understand
What you will learn
- Solve for a missing part when the total is known.
- Explain your method and check what the result means in the stated situation.
Before you start
Recognizing small groups and saying counting words; an adult may read the prompts aloud.
Keep paper nearby. Read the question once for the context, then again to identify what is known and what you need to find.
Start with a question
A box holds 9 crayons. Five are red and the rest blue. How many are blue?
Why this math matters
Find how many more supplies complete a known target. The worked example shows how to connect the situation, its mathematical representation, and a check on the result.
Set up the model
A useful answer starts with clear assumptions:
- Use the units, grouping rules, and reference whole stated in the question.
- Treat the supplied counts and measurements as exact within the classroom model, unless an estimate or a random outcome is requested.
02 · Work through the example
Follow the reasoning, one step at a time.
Try to predict the next step before reading it. After each calculation, explain why the operation makes sense and how it helps answer the original question.
Work through it with Amar
See this example unfold.
The complete worked example, one idea at a time.
Find the hidden addend
PausedQuestion: Start with the question. Paused.
Question
Start with the question
A box holds 9 crayons. Five are red and the rest blue. How many are blue?
Before you calculate
Read what is known and what you need to find. Make a prediction before moving to the first calculation.
Starts paused. Play advances through the full text at a reading pace; pause whenever you need more time. Previous, Next, and the phase buttons let you set your own pace. Playback pauses when this walkthrough leaves the screen or you switch tabs.
Your device’s reduced-motion setting keeps each phase still. Manual controls remain available. The full written solution stays below.
Represent the situation
5 + ? = 9
The red part and blue part must make the whole.
Connect the parts
Count from 5 to 9: four jumps
Six, seven, eight, nine adds four.
State and check the result
5 + 4 = 9; 4 blue crayons
Check by joining the two colored parts.
The result
5 + 4 = 9; 4 blue crayons
Check by joining the two colored parts.
Common mistakes to catch
- The missing part is not the total.
- A hidden addend can be found by subtraction.
03 · Practice independently
Try it before revealing the answer.
Use paper or a calculator as needed. Write your units and reasoning, then open the hint or explanation to check your approach.
Practice 1
Six plus what equals ten?
Show a hint
Count from six to ten.
Reveal answer and explanation
4
6 + 4 = 10.
Practice 2
Seven birds were on a fence. Some arrive and now there are eleven. How many arrived?
Show a hint
Find the jump from seven to eleven.
Reveal answer and explanation
4 birds
11 − 7 = 4, and 7 + 4 checks the total.
Take the idea with you
Find how many more supplies complete a known target.
04 · Reflect and continue
Can you explain it in your own words?
Before moving on, explain the main idea without looking at the worked example. Try both practice questions, check your reasoning, and name one mistake you now know how to avoid. Return to a step if you still need support.
Up next: Connect addition and subtraction
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