MarkT:
Most cheap breadboards have issues, like jamming easily, losing tension in the connections,
lack of contoured holes to guide wires to the contacts.
Problems which are particularly troublesome when using them as a teaching tool - when the students cant trust the connections, it makes it much harder for them to learn, especially for the ones who are having trouble with the concepts (same effect as the math teacher who slips up when doing problems on the board - the strong students follow along, notice the error as he makes it and correct for it, while the weaker ones get lost)
Also, all those problems geg much worse if you are reusing the boards a lot, esp if things that barely fit are getting stuck into the holes.
I despise breadboard, in general, and never use it, and give my friends who do crap for it - when they show me something they made on breadboard, i usually get at least five minutes to make fun of them while they look for loose connections trying to make ig work.