A science project is an academic assignment in which students perform an experiment or create a model.
In 2364, Wesley Crusher did a science project that involved a model of the tractor beam used by the USS Enterprise-D, but with a few modifications of his own added. (TNG: "The Naked Now")
In 2366, Crusher was working on a project in advanced genetics when he accidentally released two nanites on the USS Enterprise-D, leading to malfunctions throughout the ship. (TNG: "Evolution")
In 2368, Captain Jean-Luc Picard took four students with prize-winning science projects on a tour of the USS Enterprise-D which was interrupted by ship-wide disruptions caused by a quantum filament. (TNG: "Disaster")
In 2370, Jake Sisko and Nog were assigned a science project by Keiko O'Brien. They traveled to the Gamma Quadrant to perform a planetary survey with Benjamin Sisko but ended up encountering a group of Jem'Hadar and Eris, a Vorta. (DS9: "The Jem'Hadar")
In 2376, all the children aboard the USS Voyager took part in the Annual Voyager Science Fair, in which each student presented a science project. (VOY: "Child's Play")