Chavez told Buzzfeed that normally she receives a note in his folder when his balance is low and that this time the lunch lady didn't' give her son a choice between the mark or a note to take home, and stamped the mark on his wrist.
When she checked his account, there was 75 cents remaining, BuzzFeed reported.
A friend of Chavez posted a photo on his Twitter account showing the stamp.
School principal Stacey Orest said that the cafeteria worker was supposed to ask whether students want a stamp or a reminder slip and that officials will be reviewing the incident with the worker in question, BuzzFeed reported.
A spokesperson for the Paradise Valley Unified School District, which oversees Desert Cove Elementary, told The Huffington Post that the district discontinued the policy of using the stamp a few years ago and that the school will be sending letters home when there's a low lunch money balance.