Why not piano lesson for the Lisa? Why not skates lesson for John? Why the children also complaints when they have to go and attend the new theatre classes? All these questions will turn into moan and wail when the time went away and no action is taken.
The first thing is to enquire the children that why they are resisting with the present class and why they now do not like to attend it.
Do the same questions from the teachers, so to dig out the main cause of such resistance. Do not just ignore this problem rather figure it out the reason and solve it.
Sometimes children resist because initially they feel that these activities are for fun and later they find out that they have to follow certain rules and regulations. Some children balk from structured environment and sometime from the painful activities like karate.
Now keep yourself in the place of the children and think that would you like to attend it yourself? Is the program offering enough attention and motivation to the children to connect them?
It may also be possible that the number of teachers is less in the school. That is why the children are not getting the proper attention. So analyze the child to teacher ratio also. It must be 15 to 1 ratio as recommended by experts.
If you find after investigation that the school is providing interesting activities and teachers are paying proper attention too, then chat with your child.
Try to ask them about their problem. May be your children are not able to get socialized. They do not have friends to talk with and feeling social pressure. In that case help your child in making new friends there and if he/she find one, he/she show more involvement.
But after all your efforts, child still resist to go to that particular school, its time to shift him/her in another school of his/her choice. Never force the children in the case of extracurricular activities because the extra things are to bring happiness for the child nor boredom.