CHICAGO (CBS) — Now that marijuana is legal in Illinois, one Chicago public school wanted to protect its students from exposure to cannabis by changing the lunch policy.

But as CBS 2’s Jim Williams reported Sunday night, students’ parents said the school’s effort defied common sense.

Like millions of parents, Vikram Sundararaman and his wife pack lunches and snacks for their children to take to school.

“We package snacks all day for our kids,” Sundararaman said. “We give them apples. We pack their sun butter and jelly sandwiches.”

His 7- and 5-year-old sons attend the South Loop Elementary School, 1212 S. Plymouth Ct. One Friday a few weeks back, all the parents received a notice from the school:

It read in part: (I)tems for lunch and snack time must be store bought and in single-serve packaging. If a student brings non-prepackaged items to school, they will not be able to eat it during lunch or snack time.”

What was the reason for the rule? Cannabis fears.

“This policy will eliminate the risk for any students accidently bringing in cannabis infused food items to school,” the notice said.

“I was appalled,” Sundararaman said.

He was also confused. It appeared a sandwich made at home would be banned – after all, it wouldn’t be prepackaged.

A sealed bag of potato chips would also be fine, but not loose chips placed into a baggie – or so it seemed.

“I’d have to buy prepackaged Goldfish, rather than getting them bulk at Sam’s Club and putting them in Ziploc bags,” Sundararaman said.

Sundararman and the other parents quickly expressed outrage.

“There was immediately a petition that was started, because several parents make only homemade foods for their kids, and several kids only eat homemade foods,” Sundararman said.

Within days, South Loop Elementary school conceded the policy change sparked confusion and concerns. So it offered an update saying chips, fruit, and sandwiches in Ziploc bags would be acceptable.

Sundararaman said the uproar could have been easily avoided if the school had simply talked to parents first.

“I think that if you’re going to put out a policy, that policy should be well thought through. They should have – specially when we’re talking about school children – they should have the input of parents and the community before the policy is put into place,” he said.

CBS 2 reached out to the Chicago Public Schools press office. A spokesman told us South Loop Elementary acted alone, and their rule did not reflect a citywide policy.