you can help a student, but make sure they do it on thier own so they can learn the material.
I have had many students that are very disapointed in themselves and even start to lose motivation when they make a mistake in lab. My response is to ask them "well, did you learn anything?" They always say yes. Then I add "That's great! That's why your here right?" We should always try to show the students that even what may appear to be a failure is a good learning experience.
Learning from there mistakes is key
i also tell the students it is ok to make mistakes here at the school. and it is better here than out in the field on customers bikes
I always let the student know that it ok to make a mistake as long they learn from that mistake.