Grade 1 · Compare by making pairs · 171 of 750
Compare by making pairs: first group: 9; second group: 15
Two groups at a classroom activity hold 9 counters and 15 counters. Find the larger group and the difference between the two counts, 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
Two groups at a classroom activity hold 9 counters and 15 counters. First find the larger group and the difference between the two counts. Then answer: How many objects must be added to the smaller original group to make the groups equal?
Use this scratch space or work on paper. Your notes stay on this page and clear when you leave. Answers are for self-checking; they are not automatically graded.
A starting point
Pair one object from the first group with one from the second. Matched pairs account for an equal part of both groups; the unpaired objects show exactly how much larger one group is.
Work through the reasoning
Step 1
Identify the quantities and the task
Two groups at a classroom activity hold 9 counters and 15 counters. The first task is to find the larger group and the difference between the two counts. Pair one object from the first group with one from the second. Matched pairs account for an equal part of both groups; the unpaired objects show exactly how much larger one group is.
Step 2
Calculate the original result
9 < 15; difference = 6. 9 pairs can be formed. The difference is 6, so a difference of zero would mean equal groups.
Step 3
Complete the follow-up calculation
How many objects must be added to the smaller original group to make the groups equal? 6 objects. The smaller count 9 plus this difference equals 15.
The answer
9 < 15; difference = 6. 9 pairs can be formed. The difference is 6, so a difference of zero would mean equal groups. Follow-up: 6 objects. The smaller count 9 plus this difference equals 15.
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.
Use Play, Pause, and the timeline to inspect the construction. Reset restores the question’s original settings. The displayed assumptions describe where this model applies.
Watch the relationship
PausedHD animation studio
From experiment to screen.
Present a crisp Canvas scene, save a full-HD image, or capture your model as a silent video.
The mathematical idea
Two groups at a classroom activity hold 9 counters and 15 counters. Pair one object from the first group with one from the second. Matched pairs account for an equal part of both groups; the unpaired objects show exactly how much larger one group is. 9 pairs can be formed. The difference is 6, so a difference of zero would mean equal groups.
9 < 15; difference = 6
03 · Reflect and transfer
Explain what changes and why.
Advance the timeline to identify the shared count before examining the objects that cannot be paired. 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.