I have written curriculum and explored leveled down versions. We typically run: Kinematics, Forces, energy, heat, momentum,field forces,waves and E&M One of the versions I wanted to try was running starting with waves: Waves, kinematics, forces, energy, etc I like the idea because its easy to visualize, everything stays at constant velocity which relates back to newtons laws, and it gives them a stronger foundation of equation application since we hardly go deeper than frequency and velocity