With a beginning audience I would stick to KISS (Keep It Simple, Sister). For instance:
starts in the corner because it is easier to make a secure group in the corner than anywhere else on the board, and it is easier to make territory. If White plays elsewhere, Black can play 
to enclose the corner. Black makes a stable group, and Black can expect around 11 pts. of territory in the corner. But Black can also expect an additional 15 - 20 points worth of territory from this enclosure. Depending on how the game develops, Black may trade these potential points for points elsewhere, or for reducing White's potential points. Most of the game is about taking away the opponent's potential points. Typically only about one potential point in seven ends up being left on the board at the end of the game.The approach at
prevents Black from making an enclosure and challenges Black for the corner. Black has a slight advantage in this corner, which is why White often plays in an empty corner instead of making an approach. Black can play elsewhere, of course, but is a two space pincer, which prevents White from making a base on the top side. This joseki was popular a few hundred years ago, and is still played today.Unlike the 3-4,
on the 4-4 settles the corner in one play, in a way. It does not make territory in the corner so all of its value is potential. It is also a flexible play, since it can develop quickly on either the top side or the left side. If White plays elsewhere, does not make much territory in the corner, unlike the previous enclosure. Another move, 
, is necessary to secure the corner. is a smaller play than the previous two plays. became popular in the 20th century, and remains popular today.This joseki is popular today. Of course, Black can pincer
, but the simple response at is good. Black usually replies to , to prevent a double approach like a White play at 3.White often continues with the slide,
, to challenge Black in the corner and to start to make a base for . Black frequently leaves this position as is for a while. makes a base for Black and threatens to pincer . White extends to 
to make his own base.And so on.
