Zac Richard, foreground, an eighth-grader at Massabesic Middle School in Waterboro, joins classmates Wednesday morning as they hurl oranges into the mouth of the Saco River from Freddy’s Beach at the University of New England in Biddeford.

The students were measuring the velocity of the river by seeing how fast the oranges flowed with the current.

The event was part of the National Science Foundation’s Spartacus Program, which partners graduate science students with local K-12 schools.