It's not necessary. One-on-two swimming class is a swimming coach teaching two apprentices. This teaching method is affordable not only for coaches, but also for parents. The price is cheaper than one-on-one, and the swimming skills are much better than one-on-one. But if one apprentice asks for leave, the other apprentice doesn't need to ask for leave, but the other apprentice can enjoy one-on-one courses at a price of one to two.