a lot of redundancy with-in the snippet, but i guess it's an ok teaching tool as you stated in ur description.

you could show them better ways to go about things tho
for 1 like how you have

unset %bombwire
unset %bombee
unset %cutwire
unset %bombwirecolor

you could do

unset %bombwire %bombee %cutwire %bombwirecolor

or name the var like %bomb.wire %bomb.ee %bomb.wire %bomb.wirecolor
then do

unset %bomb.*