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
- Explain zero as a placeholder in a three-digit number.
- 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
Write 507 as a sum of its place values.
Why this math matters
Use a place-value table to read inventory labels with zero in the middle. 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.
Write a number in expanded form
PausedQuestion: Start with the question. Paused.
Question
Start with the question
Write 507 as a sum of its place values.
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 hundreds = 500
The leading digit belongs to the hundreds place.
Connect the parts
0 tens = 0; 7 ones = 7
The middle zero holds the empty tens place.
State and check the result
507 = 500 + 0 + 7
Leaving out the zero term in the sum is fine, but writing 57 changes the number.
The result
507 = 500 + 0 + 7
Leaving out the zero term in the sum is fine, but writing 57 changes the number.
Common mistakes to catch
- Do not turn 507 into 57 by deleting its placeholder.
- Expanded parts express values, not just isolated digits.
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
Write 680 in expanded form.
Show a hint
Name hundreds, tens, and ones.
Reveal answer and explanation
600 + 80 + 0
Six hundreds and eight tens account for all six hundred eighty.
Practice 2
Which number is 300 + 9?
Show a hint
Keep a space for zero tens.
Reveal answer and explanation
309
Three hundreds, zero tens, and nine ones form 309.
Take the idea with you
Use a place-value table to read inventory labels with zero in the middle.
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: Compare three-digit numbers
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