and only in the years between when the teacher retires and dies
Actually, it would probably be transferable. It's worth more if teachers can sell it -- if a student starts working, that stake represents a fraction of the next forty years worth of earnings, but the teacher might expect to spend it over the next ten (and since it is equity, rather than fixed income, it might not be an appropriate thing to own for retirement). So making it something the teacher can sell to invest the proceeds in bonds would be fine -- although they could just sell and invest in the future income of a public school teacher, which apparently has the stability of a T-Bill and the growth rate of Google.
Actually, it would probably be transferable. It's worth more if teachers can sell it -- if a student starts working, that stake represents a fraction of the next forty years worth of earnings, but the teacher might expect to spend it over the next ten (and since it is equity, rather than fixed income, it might not be an appropriate thing to own for retirement). So making it something the teacher can sell to invest the proceeds in bonds would be fine -- although they could just sell and invest in the future income of a public school teacher, which apparently has the stability of a T-Bill and the growth rate of Google.