Registration is underway for spring classes at the Leventhal-Sidman Jewish Community Center (333 Nahanton Street) in Newton.  Classes begin during the week of April 6 and are open to the entire community.  Classes for children include aquatics, ballet, dance, gymnastics, soccer and tennis.  Classes for adults include painting, dance, basketball leagues, tennis and writing.  View entire listing of classes and register online at bostonjcc.org or call 617-558-6419.