The student puts the first leg on the shelf.
text: This shelf is going to be the middle shelf, so you should put it should align with the middle holes of the legs.
text: That would be the top shelf. Please make it so it's the middle shelf.
text: So the shelf is good, but you could put the leg a bit more down on the way which aligned with the holes in the middle of the leg.
text: Please look at the leg, and you consider two sets of holes, so please use the second one.
text: Hum.