Posture supported upper body exercises are great to focus in on form and muscle contraction. Isolating your triceps in this way allows you to focus on the stretching and squeezing parts of this motion. These are great exercise to implement at any point in your workout, especially as a superset with chest movements.
Start with your feet hip distance apart, hinging at the waist. Place your hand on a bench/box for support. Keeping your back straight, move your arm to a ninety degree position to stretch your tricep. Then squeeze your tricep, moving your arm to straight. Focus on stretching and squeezing your tricep with swinging your arm or moving your stance.