Help teach/supervise kids.
Some days we host large groups of youths and are looking for volunteers to serve as station leaders to help instruct/monitor the smaller groups work. For example, one school brings 140 students at one time and I would prefer to break them into smaller groups. They have teachers there to watch over the kids, but it is helpful to have experienced people make sure the seeds and plants are planted at the optimal depth and spacing in each group. One station might be to transplant peppers into the rows of plastic mulch. Another station might be to plant seeds into flats. Another station might be to plant string beans into a row.