I've thought a lot about climbing training and some about discipline...
One possibility might be to place a hostile creature above a small area where the children are in a way that helps promote climbing (I've seen dwarves climb under this situation before)
C = cage built
+ = doors
# = walls
. = floors
_ = channel
space = open space
Z1
#########
##......#
## .#
## .#
+C .#
## .#
## .#
##......#
#########
Z0
#########
#########
#_.....##
#_.....##
#_.....##
#_......+
#_.....##
#########
#########
Uh basically trap a hostile creature and dig out a room like I showed (though you can work on the design). Link the cage to a lever, put the kids inside on the bottom, lock the doors and pull the lever.
The key features of the room being:
- Monster in a cage that can be released, but has no where to go. The floor tile its on should be an overhang so it can't climb down (it shouldn't try to anyways, but make it a monster that can't climb as well)
- Overhang where the monster is also keeps dwarves from climbing up to it to fight it.
- On the other walls of the room have ledges that the scared dwarves can climb up and down from (put an exit here probably in case they get stuck). Frightened dwarves seem more willing to climb to get away from threats than normal disciplined dwarves
You could experiment with some sort of reveal mechanism for the monster to provide repeated scares -> hides -> scares, and what not, but maybe a design like this would work to some extent?
In either case it seems like you need to frighten dwarves to encourage them to climb, if children can even climb at all. For discipline I'd think you just need a clear ray to the dwarves so they get scared, but something like a pit or other inaccessible terrain so they don't just rush and attack. Monsters have to be sufficiently scary as well I'd imagine, something like a Giant Rat doesn't cause much fear. You need undead or something like that.