DOUGLAS COUNTY, Colo. (CBS4) – Now that school is back in session, districts are working to make sure students stay safe, and that includes on the school bus.

Bus drivers across the Denver area are using pieces of paper to help make sure students are home safe. In Douglas County, they’re going high-tech.

Per a Colorado Department of Education regulation, school bus drivers must check their bus at the end of their routes to make sure no child is stranded. It happens to at least one child every day across the country.

While most drivers use signs, some Douglas County busses are equipped with an alarm system. If the driver doesn’t walk to the back of the bus to check for sleeping students, a loud alarm sounds.

“You’ll start hearing that beep,” said Susan Nowland, Douglas County School Bus Terminal Assistant Manager. “In order for the driver to turn the alarm off, they have to turn the key to the left and it requires them to walk to the end of the bus.”

No child has been stranded in Douglas County since the 1990s thanks to the “low-tech” sign system.