Collision not working correctly

I have a student who is working on a rollercoaster quiz. He would like for the rollercoaster to stop when the rollercoaster reaches a knowledge checkpoint. At this point the student must answer the questions correctly before moving on. He has tried multiple things like moving the code around and replacing blocks. But, it still doesn’t work. Is there a simple solution to this besides creating functions? Please help!
[CoSpaces Edu :: Rollercoaster example]