Write to an orphanage in your locality and offer to volunteer your time to teach the kids for free.
Here is a sample letter.
To Angel Home,
I am writing to know whether you are in need of additional volunteers at the moment. I am a second year college student. Now that my examinations are over I have plenty of free time on hand which I do not want to waste by sitting in front of the TV.
Teaching has always been my passion so I thought I would spend this summer vacation teaching the kids at your orphanage. It would also help me to get some experience in teaching. I can volunteer my time in the mornings and in the evenings. If you could accommodate this request, I would be most grateful.
I look forward to hearing from you,