(CNN) -- The Saghin family was getting ready for church last month in Phoenix when 2-year-old Brooke sneaked out a back door that had been left open, fell into a swimming pool and started to drown.
By the time Brooke's mother, Kim, pulled her out, she wasn't breathing. Brooke's 9-year-old brother, Tristan, wasn't about to let his kid sister die.
He told his grandmother to call 911 -- an impressive feat for any kid -- and then he did something even more remarkable:
"Tristan jumped down and started doing CPR. He just did it," Tristan's father, Chris Saghin, says. He remembers his son telling him, " 'I really didn't think. I just knew I had to do something.' "
Tristan knew how to save his sister's life only because his parents had taught him.
"He plays army and medic all the time. He wants to be a medic," Saghin says. "It's kind of his passion."
That passion has made Tristan an inquisitive little boy. He was watching a movie -- the war film "Black Hawk Down" -- and he took notice when a character performed CPR on a victim.
" 'Hey dad, how's that actually keeping him alive? He's dying,' " Saghin recalls his son asking.
Chris and Kim seized the opportunity and taught Tristan CPR on a full-size Halloween skeleton they had in the house.
"You don't expect that to ever come to a place where it saves your daughter," Saghin says. "He feels proud that he did it, and we tell him, 'We're real proud of you.' "
'Almost all children will be a hero'
Most children can be taught to handle an emergency. The first step is to teach them how to dial 911. You can unplug a landline and teach even a 3-year-old to dial the numbers.
Kids can be taught to be mini-EMTs while waiting for help to arrive.
"Any child can be taught to call 911, but every child can be taught to do more in an emergency," says Dr. David Markenson, a pediatrician in New York, who advises the American Red Cross on child safety and first aid.
A 4-year-old can learn to treat cuts and scrapes. An 8-year-old can be taught to help a person who is choking, and studies show they're also smart enough to use automated external defibrillators when trained. Studies show a 9-year-old can learn and apply CPR. An 11-year-old can learn how to tend to bee stings, allergic reactions and burns. A 15-year-old can become a certified swimming lifeguard.
Children are different: Some will want to spring into action in an emergency, while others will freeze up.
"There are kids who always feel like they're the in-charge kids," Markenson says. "The key is giving them the skills to use that desire to be in charge."
Fear may paralyze kids who aren't so take-charge, so parents and teachers need to help them work past that emotion.
"You have to tell them that it's OK to feel that way," says Markenson, who suggests parents tell their children, "When you go to help someone you might be nervous. It might be you see things you haven't seen before. What you have to remember is you're helping someone."
Child safety experts advise telling kids to count to five, or to close their eyes and take a breath. The idea is to break their contact with the emergency for a second, until they can refocus.
"Almost all children will be a hero if the parents have told them this is the right thing to do," says Markenson. "Even the quiet, shy kid can really shine in an emergency."
Here are five emergency situations where you can teach your child to be a hero and save a life.
Emergency No. 1: Choking
Grade-school kids are old enough to assist a choking victim. Kids can lean the person forward and then slap him or her on the back. The American Red Cross recommends a series of five blows to the back, followed by five "abdominal thrusts" -- teach your child to make a fist, put the thumb-side of that fist just above the person's belly button, then push. They can grab their fist with their other hand for more power.
Emergency No. 2: Bleeding
Blood can be a ghastly sight for children, especially if there is a lot of it. You can prepare your child for such an encounter by starting with something mild, turning a nosebleed into a teachable moment.
"The approach to a nosebleed is the same approach to all bleeding, which is direct pressure," Markenson says.
Have your child push on his nose to stop bleeding. After the drama lets up, tell them they can help someone else who is bleeding in the same way, by pushing on the part of that person's body that is bleeding.
Emergency No. 3: Fire
If someone catches fire, your child can yell and remind that victim to stop, drop and roll.
"The motion of rolling will smother the fire," says Lorraine Carli, vice president of the National Fire Protection Association.
The association and the Home Safety Council don't recommend teaching children how to use fire extinguishers, because fire extinguishers may be difficult to operate and kids may lose valuable time getting to safety.
"If a kid knew how to use it and could use it, there wouldn't be harm," Carli adds.
Emergency No. 4: Drowning
Do the experts suggest a child toss a floatie or pole out to a drowning person? Or should they do absolutely nothing?
In most emergencies you want your child to jump in and help -- but not this one -- not when a person is in trouble in the water.
"You don't want a kid going out there," says Dr. Sara Ross, assistant medical director of Safe Sitter, a nonprofit that prepares teens for watching kids. "That has high potential to be a multivictim accident."
Panicky victims can drag their would-be rescuers underwater. While kids, especially those who are strong swimmers, may have that instinct to jump in, safety experts say there are better approaches.
"There are a lot of people who try things and it works out. It doesn't mean it's the best thing to try," Markenson says. "In most cases there's something you can throw to them to keep them afloat."
Older teens can learn when to enter the water as a trained lifeguard. The American Lifeguard Association and American Red Cross Lifeguarding have information on how teens 15 or older can become a lifeguard.
Emergency No. 5: A person isn't breathing
When Brooke Saghin wasn't breathing, her 9-year-old brother Tristan pumped his sister's heart while the family waited for rescue workers to arrive.
You can teach your child CPR in three easy steps. First, instruct him to put the heel of his hand on the victim's breastbone in the center of the chest. Second, put the other hand on top and interlock the fingers. Third, press straight down into the chest 100 times in one minute.
Don't worry about mouth-to-mouth breaths. For bystanders -- like Tristan or your little hero -- experts recommend a new version of CPR that requires using only hands.
"The single skill you have to teach is push in the middle of the chest -- hard and fast," Markenson says. "Children as young as 3, 4 and 5 can be taught how to do that. Will they do it perfectly? No. Could they help someone? Yes."
The American Heart Association can help you find a CPR class in your area. It also has a how-to CPR video. There's no minimum age, although kids around 9 and older are stronger and better able to do chest compressions.
The Empowered Patient is also a big believer in this tip: Along with teaching your children holiday carols and the national anthem, you can introduce them to a throwback -- the Bee Gees' song, "Stayin' Alive." Teach them to deliver chest compressions to the beat of the song. It has the same rhythm as life-saving CPR. The Empowered Patient website has more information on the technique.
You can also teach your child how to use an automated external defibrillator. A defibrillator shocks the heart to beat in a normal rhythm. Studies show even a third-grader can use a defibrillator if he or she is taught how to peel off the backing on the chest pads.
"Grade-school kids can actually use that device because it's so self-explanatory," Ross says.
Tristan's father is grateful they took the time to teach their son to save a life.
"He got her breathing. She would have had brain damage or worse," Saghin says. "We're so blessed."
Elizabeth Cohen, Senior Medical Correspondent, and Sabriya Rice, CNN Medical Producer, contributed to this article