Learn with Amar
Teaching video
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Grade 5 chapters and video availability01 · Read and understand
What you will learn
- Use a fixed correspondence between drawing and actual lengths.
- Explain your method and check what the result means in the stated situation.
Before you start
Multi-digit operations, equivalent fractions, decimal place value, and rectangular area.
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 diagram states that 1 cm represents 2 m. A wall is drawn 4.5 cm long. What length does it represent?
Why this math matters
Use labeled scale diagrams to connect manageable drawings with larger spaces. 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 a simple drawing scale
PausedQuestion: Start with the question. Paused.
Question
Start with the question
A diagram states that 1 cm represents 2 m. A wall is drawn 4.5 cm long. What length does it represent?
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
Scale = 2 m per drawn cm
The rule connects two different measurement contexts.
Connect the parts
4.5 × 2
Every drawn centimetre represents two actual metres.
State and check the result
Represented length = 9 m
The decimal half-centimetre represents one additional metre.
The result
Represented length = 9 m
The decimal half-centimetre represents one additional metre.
Common mistakes to catch
- Keep drawing units separate from represented units.
- Scaling the printed image changes its stated centimetre-based scale.
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
At the same scale, how long should a 7 m wall be drawn?
Show a hint
Reverse the correspondence by dividing by two.
Reveal answer and explanation
3.5 cm
7 ÷ 2 = 3.5.
Practice 2
If the printed diagram is enlarged, can the old 1 cm rule be used unchanged?
Show a hint
Printed centimetres now cover a different original span.
Reveal answer and explanation
No
A physical resize changes the length scale unless the scale is adjusted.
Take the idea with you
Use labeled scale diagrams to connect manageable drawings with larger spaces.
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: Convert a decimal mass to grams
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