California schoolchildren lined up Saturday to trade in their guns -- the toy kind, made out of plastic.

In exchange for the colorful toy firearms, Strobridge Elementary School students received books and a chance to win a new bike, Bay News 9 reports.

Strobridge’s principal, Charles Hill, said the Castro Valley school held the exchange because he thinks playing with toy guns increases the chance of children using real ones when they grow up.

A Hayward police officer was also at the event to teach bicycle and gun safety, and the Alameda County Fire Department had a crew discuss fire safety, the Silicon Valley Mercury News reports.

But at least one gun rights advocate questioned the principal’s stance on guns.

"Guns are used in crimes, but they are more often used in defensive ways which prevent violent crime from occurring in the first place,” said Yih-Chau Chang, a spokesman for the Responsible Citizens of California.

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