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 3 chapters and video availability01 · Read and understand
What you will learn
- Use stacked marks to show repeated numerical observations.
- Explain your method and check what the result means in the stated situation.
Before you start
Place value through hundreds, addition and subtraction, equal groups, and equal shares.
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 dot plot shows 2 dots at 3 books, 1 dot at 4 books, and 3 dots at 5 books. How many children were surveyed?
Why this math matters
Plot small measurement lists to see which values occur repeatedly. 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.
Read repeated values in a dot plot
PausedQuestion: Start with the question. Paused.
Question
Start with the question
A dot plot shows 2 dots at 3 books, 1 dot at 4 books, and 3 dots at 5 books. How many children were surveyed?
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
2 + 1 + 3 = 6 dots
Each dot represents one child, not one book.
Connect the parts
Counts at values: 3, 4, 5
The horizontal positions show books per child.
State and check the result
6 children
A plot separates the measured values from how many observations share them.
The result
6 children
A plot separates the measured values from how many observations share them.
Common mistakes to catch
- Adding positions is different from counting observations.
- Each mark must represent the same number of observations.
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
How many children reported five books?
Show a hint
Read the stack at five.
Reveal answer and explanation
3
There are three observation marks above five.
Practice 2
How many books in total did all six children report?
Show a hint
Weight each book count by its dots.
Reveal answer and explanation
25 books
2 × 3 + 1 × 4 + 3 × 5 = 6 + 4 + 15 = 25.
Take the idea with you
Plot small measurement lists to see which values occur repeatedly.
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: Reason with a larger graph scale
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