[JavaBrewer]

I rarely used the back brake - almost never in slippery conditions. Too easy to lock the back tire. That said in dry conditions I did use the back brake but only to maintain balance. Stay off the road center (oil), road paint, and brake with the front early. Sounds like your son needed to get the back tire rolling again (let go of brake) but was pressed for time/space at the stop light. Good thing the speed was low and he was unharmed.