Remember the balls, not the places
At level 1, two of the six balls are marked. Study that group for as long as you need. Movement begins only when you choose Ready, follow them.
The marks then disappear, and all six balls look alike. Follow the same two balls as they move. Their starting places are not the answer.
The pictures in this lesson are static teaching examples, not a tracking trial.
A change of direction does not change the target
The balls move for six seconds at level 1. They can change direction at the edge or when they meet another ball. A target stays a target after either turn.
This picture reveals the original two targets at the end of the same generated example. In the practice, you choose your answers before that reveal.
When balls come close, keep following the ones you began with. Do not switch to a nearby ball just because it is easier to see.
Choose the original targets
Movement has stopped. Number labels now help you select balls; the numbers were not visible while they moved.
Select the two balls you followed, then choose Check selection. Selecting a ball again undoes that choice. Which rule should guide your answer?
Try it
What should you select after the balls stop?
- Any balls near the two starting places
- The same two balls that were marked at the start
Show the answer
The same two balls that were marked at the start
Correct. A target keeps its identity as it moves and changes direction. Choose those original balls at their final positions.
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Practice Multiple-object tracking