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 2 chapters and video availability01 · Read and understand
What you will learn
- Count up to a dollar using one hundred cents.
- Explain your method and check what the result means in the stated situation.
Before you start
Counting and comparing whole numbers, basic addition and subtraction, and recognizing simple shapes.
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 pretend shop item costs 68 cents. You pay one dollar. What change is due?
Why this math matters
Use play money to check both sides of a simple purchase. 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 change from one dollar
PausedQuestion: Start with the question. Paused.
Question
Start with the question
A pretend shop item costs 68 cents. You pay one dollar. What change is due?
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
$1 = 100 cents
Write payment and cost in the same unit.
Connect the parts
68 to 70: 2 cents; 70 to 100: 30 cents
Count up through an easy ten.
State and check the result
2 + 30 = 32 cents change
68 cents plus 32 cents checks the dollar.
The result
2 + 30 = 32 cents change
68 cents plus 32 cents checks the dollar.
Common mistakes to catch
- Do not mix dollars and cents as if their units match.
- Change is the unused part of payment, not the price.
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
What change comes from $1 after a 75-cent purchase?
Show a hint
Complete one hundred cents.
Reveal answer and explanation
25 cents
75 + 25 = 100.
Practice 2
An item is 40 cents and change from $1 is 60 cents. What checks this?
Show a hint
Cost plus change equals payment.
Reveal answer and explanation
40 + 60 = 100 cents
The two amounts account for the entire dollar.
Take the idea with you
Use play money to check both sides of a simple purchase.
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: Read tally marks in fives
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