MOUNT LAUREL — The Countryside Elementary School on Schoolhouse Lane will be open from 7 to 9 p.m. Friday to celebrate four decades of education. The event will be the culmination of daylong classroom activities. Visitors will be greeted in the main lobby by new mosaic artwork created especially for the occasion by students and Jackie Stack Lagakos, an artist in residence from the Perkins Center for the Arts in Moorestown. The work, which is being dedicated Friday, was designed by Countryside art teacher Jennifer Giannattasio. The project was funded by a grant awarded to the school last year through a TerraCycle "upcycling" contest.