Pic 1) Some kind of succulent, not active and possibly poisonous if in the euphorbia family, can't really tell from the pic.
pic 2) Cereus Peruvianus, a common but inactive look-alike to members of the active trichocereus family.
Sorry, niether are of any use as plant teachers although the cereus peruvianus if in the proper climate bears an apple-like fruit which i am told is quite tasty either raw or cooked.