Students need to have productive things to do in the summer while they are not in school. It is not good for students to just sit around with nothing to do for long periods of time. Giving them something to do - a summer job, summer camp or other productive activities - will develop their character and build a strong work ethic.
Many students view summer as a time for relaxation - which can get them into trouble. It's a good idea to give students a range of mandatory activities to do during the summer because then they can learn valuable life skills, maybe earn some money, but mostly become contributing members of society.
Kids, whether in primary or secondary school, should have the entire summer to relax and have fun. Throughout the entire nine months of the school year, they are continually working very hard to assure that they are pleasing their parents, themselves, and their teachers, not to mention keeping their all important grades up.
While some students will make a choice or be encouraged by their parents to do productive things in the summer while they are not in school, that should be a personal choice for each family. If a student just wants to relax and have fun during the summer and their family is okay with that, it's fine.