Some admitted they never thought about not letting in a person who claims to be a repair man before checking identification and calling the company they work for.
"I learned a lot tonight," said Jessica Saunders, 16, of Mercersburg. "I learned more than I thought I would."
Teens who think all there is to babysitting is seating the kids in front of the television until bedtime are wrong.
"If an emergency happens and you're not prepared, then you won't know how to react," said Mercersburg Police Officer Bill Sheppard, who conducted the first in a series of babysitting classes held in the fire hall.
Some class participants took notes as Sheppard instructed them on the use of 911, a call most of the teens in attendance haven't had to make before.
Since parents are often in a rush to leave, Sheppard advised the teens to arrive a little early at the household where they'll be babysitting so they can get important information.
"Ask questions. You're not being nosey. You're just trying to do the best that you can as a baby sitter," Sheppard told the group.
The teens also learned tips to avoid potential accidents and emergencies.
"I wouldn't normally ask about medications the kids are supposed to take," said Ellie Knott, 13, of Mercersburg, who often looks after her 2-year-old sister. "I wouldn't think to go around and lock the doors and windows."
Jonnette Shuey, 13, of Mercersburg, who baby-sits two toddlers every other Saturday, said from now on she'll ask for identification from people who knock at the door.
The baby sitting class was the first in a six-week series held every Monday night from 6:30 to 8 p.m.
Upcoming classes include fire safety, first aid, how to respond to choking and CPR certification.
Those who complete the class successfully will receive a certificate from the Mercersburg Jaycees and their names and phone numbers will be available at the police and fire departments for referrals.
"Hopefully you'll get more jobs out of this," Sheppard told the group.
Anyone interested in the class can still sign up at the Mercersburg Police Department, located beside the Borough Hall on South Main Street.