I spent a few months in Hanoi, teaching french at a primary school and English at an University. The kids were really sweet and involved, and so kind to me and the other teachers ! I had no experience in teaching prior to this, but I loved it. At uni, I got to know the students and they were really nice and fun :) It was a real sharing experience.
Also, at the house, we were dozens of volunteers from all around the globe, and I loved living in such a community which such wonderful people ! While I had privacy when I needed it, I also always had friends to hang out with. The immersion in the Vietnamese culture was great : I had an introduction lesson to Vietnamese, all the teachers and students were Vietnamese, the staff of VPV was Vietnamese (and really really friendly !), and all the women at my yoga classes were vietnamese !
I really recommend this volunteering if you're travelling alone, or with friends, whatever your age (even though there are mostly people around twenty in the house).