Grade 1 · Align ends to compare lengths · 711 of 750
Align ends to compare lengths: first strip length: 14 units; second strip length: 16 units
A design for a classroom activity uses strips of lengths 14 and 16 equal units. Find the longer strip and the difference between the lengths, explain the calculation, and check a related question.
Try the question, use a hint when you need one, and compare your reasoning with the worked solution. The animation starts with this chapter’s values; changing its controls explores a new case.
01 · Make a prediction
Your practice question
A design for a classroom activity uses strips of lengths 14 and 16 equal units. First find the longer strip and the difference between the lengths. Then answer: What extension would make the shorter strip exactly as long as the longer one?
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A starting point
Length comparisons require a common unit and aligned starting endpoints. A longer drawing caused only by a different display scale would not be a valid comparison.
Work through the reasoning
Step 1
Identify the quantities and the task
A design for a classroom activity uses strips of lengths 14 and 16 equal units. The first task is to find the longer strip and the difference between the lengths. Length comparisons require a common unit and aligned starting endpoints. A longer drawing caused only by a different display scale would not be a valid comparison.
Step 2
Calculate the original result
Length difference = |14 − 16| = 2. The longer strip reaches 16 units from the start; the shorter reaches 14 units.
Step 3
Complete the follow-up calculation
What extension would make the shorter strip exactly as long as the longer one? 2 units, because 14 + 2 = 16.
The answer
Length difference = |14 − 16| = 2. The longer strip reaches 16 units from the start; the shorter reaches 14 units. Follow-up: 2 units, because 14 + 2 = 16.
Compare the method as well as the result. A different valid method may reach the same answer. Keep exact values until the last step when the question asks for rounding.
02 · Explore the model
See the mathematical relationship move.
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Watch the relationship
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The mathematical idea
A design for a classroom activity uses strips of lengths 14 and 16 equal units. Length comparisons require a common unit and aligned starting endpoints. A longer drawing caused only by a different display scale would not be a valid comparison. The longer strip reaches 16 units from the start; the shorter reaches 14 units.
Length difference = |14 − 16| = 2
03 · Reflect and transfer
Explain what changes and why.
Trace both strips from their shared starting line. Compare the endpoints after both complete lengths are visible. Explain which quantity changes and which relationship stays valid. Use the starting values again before checking your written answer.
This is a distinct guided scenario using a reusable mathematical model. Similar-looking diagrams can represent different given values and conclusions; they are not different mathematical theories.