Grasp a pair of dumbbells and stand with your knees slightly bent, hands by your sides, palms facing in. Curl the weight in your left hand toward your shoulder, but don't rotate your wrists as you did in the standing dumbbell curl; the top plate of the dumbbell should face up throughout the movement. Lower your left arm, then bring your right arm up and continue this alternating pattern. Keep your elbows stationary throughout.
Sit on the end of a coffee table or low chair with your legs apart. Holding a dumbbell in your left hand, lean forward and position your arm so that your left elbow is pressed against your left inner thigh. Keep your back flat. With your palm facing up, curl the weight straight up by contracting your biceps, then lower and repeat. Complete all the reps on your left side, then switch to your right.