Grade 2 · Data
Bus-stop counters: compare counts on a common scale
A survey display at a transport model records three category counts: 18 passenger counters, 17 passenger counters, and 12 passenger counters. Change the controls and explain what the animation reveals.
Predict what will happen, press Play, then pause and explain what changed. Every control also works without playback.
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.
Understand what you are seeing
The idea behind the motion.
A survey display at a transport model records three category counts: 18 passenger counters, 17 passenger counters, and 12 passenger counters. A bar graph compares category counts using a common baseline and a common vertical scale. The height represents a count; the width of a bar is decoration and does not represent another variable. The largest final category has 18, the smallest has 12, and all categories together contain 47.
A relationship to keep
Total = 18 + 17 + 12 = 47
Read the symbols alongside the explanation. A diagram shows the relationship; the assumptions tell you when it applies.
- STEP 1
Read the starting situation
A survey display at a transport model records three category counts: 18 passenger counters, 17 passenger counters, and 12 passenger counters. Identify what each number measures before changing a control; the worked example refers to these starting values.
- STEP 2
Follow the mathematical change
Advance the timeline to add the observations to their three categories. Compare the live counts, then inspect the final bar heights on the shared scale. Pause on an intermediate frame and compare the picture with the live readouts.
- STEP 3
Explain and test the relationship
The largest final category has 18, the smallest has 12, and all categories together contain 47. Change one input, predict its effect, and test whether the same relationship still works.
Your turn to explain
Make a prediction. Test your reasoning.
Bus-stop counters: use the original situation. A survey display at a transport model records three category counts: 18 passenger counters, 17 passenger counters, and 12 passenger counters. How many observations separate the largest and smallest final categories?
Use the values specified in the question. Reset restores the initial values for this investigation.
Compare your explanation
6 observations, found by subtracting 12 from 18. The sum answers a different question.
Work through a full lesson
Connect the animation to a worked example and practice questions.