My testimony before the Boston School Committee meeting is here. My testimony starts around 23:35. Boston School Committee member Mary Tamer's exchange with legal advisor Alissa Ocasio begins at around 3:04:18. They agreed that Ms. Ocasio would provide the school committee with information about what other Massachusetts school districts do with respect to waivers of liability in permission slips. As far as I know Ms. Ocasio has not responded to that request yet. (But the answer is, it varies. Some districts use waivers and others don't. However, that is irrelevant. Other school districts should look to Boston, not the other way around.)
See my other posts on the issue here, here, and here.