GROTON, Mass. (AP) – Police here are searching for a different kind of penny pincher. More than 100,000 pennies are missing from Groton-Dunstable Middle School, where students have been trying since February to collect a million of the coins to better understand the magnitude of the Holocaust.

Selectmen Chairman Peter Cunningham said students noticed this week that the 100,000 pennies – more than half of the total collected – were missing from plastic water jugs and coffee cans in the school. Whoever took the cash likely did so over a period of time, because 100,000 pennies weighs about 550 pounds. No arrests have been made, but Cunningham said an adult was suspected.

“You have to be pretty desperate to steal kids’ pennies,” Cunningham told The Sun of Lowell. “It just undercuts the kids’ trust.”

The What is a Million? Project was started last year by teacher Niki Rockwell, who was hoping to give students learning about the Holocaust a visual representation of how many children died.

“It really breaks my heart that people will take money from children who are raising money to remember children who died in the Holocaust,” 14-year-old Danya Degen said. “But we’re going to try and raise what we lost. We won’t quit.”