LOS ANGELES — For Rebecca Zeitlin, packing her 5-year-old son’s school lunch is always full of surprises. Offer him a peanut butter and jelly sandwich at home and he won’t touch it. But pack it in his lunch with fruits, vegetables and a small treat and he’ll dive in.

He will “chow down” on applesauce at preschool parties. But if she served him applesauce at home, “he’d look at me like I was crazy,” Zeitlin said.

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