This is a free website of science/math simulations. There is also a professional learning community complete with lessons submitted by teachers and approved by the developers. You can expect some high quality materials.
I selected a lesson plan that included a pre-test, activity and post-test. The students were shocked by their improvement from pre to post test. There is also a game that goes along with this simulation.
Since it is free, no subscription is needed. Simply go to the phet.colorado.edu website and browse the simulations. It takes time to look at the activities and suggested plans, but it is well worth it. I cannot think of a better way to teach about protons, electrons and neutrons.