There are no studies on the subject, but many schools do have it.
Some schools do and some don't
yes I have been to many places in the world and all had homework
Many do.
Almost all schools arrange a for a summer camp during their holidays.
I guess people like to get their homework done the "easy" way. WikiAnswers can be used as a source for information when doing your homework and is used in many schools.
It depends on many things: the class, the school, the teacher, the students, and the time of year (many schools don't give homework over holidays or breaks)
It's most common among Orthodox Jewish religious schools to own summer camps.
Yes, they do
No studies have been done on this
None. No schools or states have banned homework. Some schools have reduced the amount given but it is still given out.
Anywhere you find schools is going to have homework.
Australian schools do have along summer break. The summer break is a minimum of six weeks long and, in many private schools, up to eight weeks long.