00:00 Trampolines are dangerous and can lead to serious injuries, as discussed in this episode of "Stuff You Should Know."

04:36 Trampolines have been around since the 1930s and consist of a rigid steel frame with a bouncy surface made of tightly woven fabric and coiled springs.

09:38 Trampolines come in different shapes and sizes, including rectangular competition trampolines and round ones with nets for home use.

14:31 Trampolines work by combining kinetic energy from jumping with the potential energy stored in the springs, which launches the jumper back up into the air.

19:47 George Nissen and Larry Griswald met at the University of Iowa and together they built a prototype of the trampoline using a nylon mat, grommets, and bicycle inner tubes, and later introduced steel coils, ultimately trademarking the name "trampoline" and founding the Griswold Nissen Trampoline and Tumbling Company in 1942.

25:01 George Nissen took over the trampoline company from Larry Griswold and started touring around, demonstrating the trampoline and promoting it, leading to its popularity in the 50s and 60s.

29:51 Trampolines were initially used for training in tumbling and diving, as well as for helping pilots adjust to disorienting body positions, and trampolining has become a competitive sport, although it is not officially recognized by the NCAA.

35:36 Trampolining became a sport in the 60s when groups of gymnasts from different schools started competing against each other, and it eventually became an Olympic event in 2000.

40:32 Trampolining became an Olympic event in 2000, with Russia initially dominating but China and Canada also having strong trampoline athletes.

45:40 Trampolines can be extremely dangerous, with statistics showing that over a four year period in the United States, there were 93,000 emergency room visits related to trampoline injuries, including over 2,000 traumatic brain injuries in children between the ages of five and 18.

50:34 Trampolines can be dangerous for kids, causing injuries such as cracked heads, trampoline ankle, and even death, which is why safety precautions such as no kids under six, safety netting, and only one person at a time are important to follow.

55:55 Language is important and using the term "enslaved person" instead of "slave" helps to express that slavery was the result of an action by enslavers.