I always found slow flight (or at least slower than normal - say 60-70 knots) useful for students in quite early stages who were struggling with straight and level. Taking it from them, accelerating back to 90 knots and handing control back to them made them wonder what they ever found hard about S+L at normal airspeeds in the first place.
As for exercise 10A, I always demonstrated a full stall at the beginning of the exercise, otherwise the student was so frightened of stalling that they'd always lose altitude. The added advantage was that when I said we would do 10B next, there were no real concerns. I've come across some students (not my own) that had sleepless nights before doing 10B, when really stalling is no big deal (at altitude at least...).