Why learn how to fall? If you run, bike, climb (bouldering), skateboard, even just walk or hike regularly, then there will likely be a time you catch a toe, ride over a stick, or just have a foot slip out from under you. When this happens, the ground comes at you quick, and it’s not often forgiving.
When it comes to reducing the risk of injury during a fall, the best thing one can do is prolong the duration of the fall. If you are running and catch a toe on a root, or a curb, you have all that forward momentum that will send you right the ground at a decent speed to zero in an instant. The sudden deceleration will not feel good, and if you stick out an arm to catch yourself then you risk injury to the wrist, elbow, shoulder, or the bones in the forearm, along with the potential for hitting your head. The best thing to do if you fall running is to roll out of it. Besides reducing your risk of injury, it looks awesome when you roll out and get back to your feet in one smooth motion, maybe keeping your pride intact.
The best way to make sure you actually fall properly is to practice the technique of a roll. During times of stress (falling in this case) your body/brain will revert to training. When learning to shoulder roll, it is best to start from a kneeling position. From there form a diamond with your hands (like a diamond pushup.) This acts as your window for spotting your landing. Touch the ground near the foot of the leg that is up, then touch the forearm, elbow, and shoulder. Once the shoulder touches the ground, you will want to tuck yourself into a tight ball, roll across your back, to the opposite hip of the shoulder you land on. Rolling across the body will make sure you don’t spend much time on your spine. Make sure you tuck your chin to protect your neck, and again, tuck yourself into a tight ball. This will keep you from just falling onto your lower back. Practice both sides, and practice at least a few days a week. You want to be sure that this pattern is burned into your nervous system so when you do fall, it will be instinct.
After practicing from a kneeling position and getting comfortable with the motion, it is time for the next step. Move up to a standing position, and repeat the same thing you did while kneeling. You are further from the ground, so again, to keep yourself from landing on your back, tuck into a tight ball to make sure the roll is as smooth as possible. After you get comfortable starting from a standing position, it is time to move on. Now find a nice grassy spot and start jogging or running. Now under control, fall and roll out of it back up to your feet. TUCK INTO A BALL! Practice the running roll until it is smooth, then move up to a ledge, about knee to hip height, and jump off of it, land on your feet, start to bend your knees, spot your landing, and roll out of it.