I have a cracked tooth but it does not hurt much only now and again but I am too scared to tell my parents in case they get cross. What should I do ?and what would the dentist do?

I would tell your parents if I were you. It is better to get it taken care of now then later. Then they might be more upset if it could have been taken care of for less money than later. The dentist might pull it of put a filling in it or cap it.

Large fillings typically weaken teeth, especially the molars.

Chipped and cracked mean different things to me. Chipped, means a chunk broke off. Cracked means something like a hairline rack in a tooth.

I guess the question is how did you crack it? Why would your parents get upset? If you have it looked at now it will probably cost less money than if you wait for the tooth to bother you or fall apart.