For most kids it was probably around 5 or 6 years old.
But a new type of swimming lesson is cutting that age way down.
Some swim instructors are offering kids a new type of swimming lesson that can give parents a little peace of mind.
It's a scene that would make most parents hear stop, a toddler sitting by themselves on the edge of the pool, then falling in.
"Anybody who is a parent of young kids knows that it just takes a second for an accident to happen," said parent Linda Niederklein.
Leslie Harrison said she's the only instructor in Missouri or Kansas certified to teach survival swimming to young kids.
"I teach them how to swim with their face in water, roll over to rest, float, breathe and roll back over and swim to wall," she said.
It's called "swim-float-swim" and in traditional lessons, it's a skill kids wouldn't learn how to do by themselves until at least 3 or 4 years old.
"I'm not saying every child is drown proof because of these lessons but it does give added insurance that they could survive an accident," she said.
Harrison said it usually takes kids about 6 weeks to learn how to swim-float-swim, but the hardest part is getting parents through that first day.
"It's not easy to watch at times," said Leslie.
That's because in the beginning these classes do involve a certain amount of "sink-or-swim" mentality.
"I take precautions and pay attention to the body," said Harrison.
But in the end, even kids understand why it's important.
"We don't want to sink," said 5 year old Noah.
And so do parents.
"It may be hard to watch at first but it's more fun to watch in end because they have these skills," said Linda.
Leslie Harrison went through 6 weeks of training in Colorado in order to learn how to teach these lessons.
She did want to stress that it's not something parents should try to teach their kids on their own because it is dangerous for kids to swallow too much water.
She also said even if your infant learns these skills they should also have constant supervision when they're in the water.
You may be wondering how an infant child who can barely walk or talk can learn how to swim.
Harrison said kids actually have a natural instinct to swim when they're born but they lose it as they age.
The attached video may be alarming to some.