"Learning is enhanced when it is more like a team effort than a solo race. Good learning, like good work, is collaborative and social, not competitive and isolated. Working with others often increases involvement in learning. Sharing one's ideas and responding to others improves thinking and deepens understanding."
Chickering & Gamson (1997)
I strongly believe that self-esteem is raised in both sides since the tutor feels helpful and the weak learner feels supported and cared for. What's more, sometimes students may feel more comfortable or will learn best if a peer helps him/her since they have the same age, interests and needs.
I'm glad because in general I've received a positive response from parents, tutors and the helped students. I feel so happy when some tutors praise their mates for making an interesting comment or having a bright idea or when they let me know that kids are doing fine. Although the system is working well I´ll plan a brief meeting with the tutors to talk about their responsibilities, to give them some feedback, to make them do a guided self-assessment of their role and to listen to their opinions. I think that controlling these things from time to time is crucial for the system's effectiveness.
References:
Chickering, A. W, and Gamson, Z. F (eds.), Applying the Seven Principles for Good Practice in Undergraduate Education. New Directions for Teaching and Learning, no.47. San Francisco: JosseyBass, 1991.