[naters]

I’m fairly sure that “wallball” played in most elementary schools around the US is a different game than what is being referred to here. Growing up in New England, what we called wallball involved throwing a tennis ball against a wall and attempting to catch it before someone else, while the NYC handball/wallball is closer to racquetball, but played outside against a (usually) freestanding concrete wall with palms used instead of racquets.