There's good cause to be careful about this kind of pedagogy. This kind of thing is made possible by strong ethic in a school of "all for one and one for all,"

There's good cause to be careful about this kind of pedagogy. This kind of thing is made possible by strong ethic in a school of "all for one and one for all," shared by the faculty and the administration, and accepted by students and parents. If it's just a "good teacher" or two in an institution that doesn't have that ethic, using more advanced students to help less advanced ones can exploit both groups. Now, many public school teachers have to practice "guerrilla excellence" so it's a complex problem. But a kiddo who gets algebra doesn't necessarily get teaching it.