In my Introduction to Weightlifting class, one of the most popular questions is, ‘What should I do for my abs?” My reply is “Squat.” Another frequent question is, “What should I do for my back?” My reply is, “Deadlift.” Infrequently do my students take this advice; instead, they return to the cardio corner of the room and lie down on a yoga mat to do some more crunches. This session, as an example, on the day that I taught the deadlift, 3 of 7 girls in my two classes learned and tried the deadlift, whereas 0 of 25+ guys even attempted to deadlift. As for ab strength, in my circuit training class, I did a plank test this week. First time that I have done a plank in over a year. I stopped after 1:30 because of boredom. I do no abdominal or core strengthening exercises: my workouts consist almost entirely of deadlifts, cleans, front squats, overhead presses, bentover rows, and pull-ups. Students in my circuit training class who have done multiple planks (as well as numerous other core exercises) in every class period this semester, but never deadlifted or squatted, start shaking before 45 seconds is complete. That isn’t a scientific proof of the supremacy of the deadlift and squat to any abdominal exercise for core stability, but it is my observation, and the core stability benefits of the squat and deadlift are ancillary benefits, as the true purpose is lower-body (total-body) strength.
As for teaching the lifts, the two videos below show a couple ideas that have changed the cues that I use when teaching the squat and deadlift. The basic movement and teaching progression is the same, but in my unscientific experiments, I found the load ordering to make an immediate difference in deadlift performance, and a student who used to be a professional athlete was enamored with the hooking the toe on the squat.