Lesson 1 · Introduction to the Grid — Knowledge ChecksAnswer key

Do you need to change your LineTrack class to drive on the grid?

1. A.Yes — grids need a whole new class
2. B.No — a grid intersection looks just like the Module 2 cross, so LineTrack works unchanged✓
3. C.Yes — you must rewrite track_until_cross()
4. D.Only the sensor class changes

An intersection reads the same to the sensors as the circle's cross did, so the same class navigates the grid with no changes. That's code reuse.

Which LineTrack method drives the robot from where it is to the next intersection?

1. A.turn_right()
2. B.track_until_cross()✓
3. C.turn_left()
4. D.get_error()

track_until_cross() follows the line and stops when both sensors hit the intersection — one grid segment per call.

You run the program and the robot reports 'Intersection reached!' instantly without moving. Why?

1. A.The battery is dead
2. B.It started sitting on an intersection, so both sensors were already high✓
3. C.track_until_cross() is broken
4. D.The threshold is too low

If it starts on a cross, is_at_cross() is already true and the follow loop exits at once. Back it onto a plain line segment to start.