Re: Ukemi problems
The (excellent) links by Robin show someone who is already unafraid of falling.
If someone is having trouble at the start they should be on the crash-mats, if available. I've seen more people leave a club and never come back through bad introductions to a breakfall/ukemi. For beginners it requires specific, constant supervision and control.
A sound lack of fear with falling enables a student to practice more freely.
However these comments don't take into account that learning to roll/fall hurts, tricking gravity/fate takes some skill and it doesn't come cheap.
Worth having though.