I experienced internship last spring vacation, I mean, from the end of January to the middle of February.
In my case, I went to Los Angeles, in the United States, and joiend an elementary school to help teacher, so called "assistant teacher".
What is the good point of internship is that you can make really good experience through work. You can work that you want in school days. That's amazing thing, isn't it?
Well, I have to mention about weak point. You cannot enjoy your vacation. If you think that you would like to work, it means that you will have no time to play, especially weekdays.
Anyway, I strongly recommend internship. Of course, it will be shorten your vacation that I mentioned before, but the experience through work will be your best memory in your school days, definetely.