Is it 6 years OR 60lbs, or 6 years AND 60lbs? I always thought it was "and" but after being told that only 3 kids in DS's class had booster seats on their field trip, now I'm thinking it's "or." How many states are 8 years and/or 80lbs? I think that's what it needs to be here. I would be freaked out driving a bunch of 6 year olds around without boosters.