Jumping jacks get your whole body moving and have plenty of versatility. There are a lot of ways to have fun with jumping jacks that don't bring up uniformed workouts in your middle school gym class.
Konforti's form tip:
Jump your legs out as you bring your hands overhead, then jump back to standing.
Or, instead of your run-of-the-mill jumping jacks, spice them up with a more dynamic version that can help you burn even more calories. With each jumping jack, cross your legs, alternating which leg goes in front while also keeping your arms at chest height and crossing them. If you're really feeling up for a challenge, add in a squat as you hop your legs out. It's effective and much more entertaining.