On the first day of school at Treasure Hills Elementary in Harlingen, Ashley Barker double checks her long list of to-do's.
It includes making sure her youngest children, Darby and Paisley, aren't left behind in the vehicle.
"I'm a mother of 3... And you're juggling so many things all the time... I think anybody could... No matter how perfect they think they may be," she said.
Officer Sal Carmona with the Harlingen Police Department showed how quickly injury, even death, can result when a child is left in a hot car.
He used a special temperature gauge to compare readings outside and also in his squad car.
Within the first 5 minutes of the demonstration the temperature inside the vehicle rose to 127 degrees.
"Within 10 minutes that baby is going to be escalated to heat exhaustion and then behind heat exhaustion, heat stroke... And then we're going to have a fatality in that car," the officer said.
Texas leads in the nation in the number of hyperthermia deaths of children in vehicles.
There have been two fatalities in the Rio Grande Valley this year.
Officer Carmona said parents, more often than not, simply forget to look in the backseat of their vehicle.
It could quickly prove to be a fatal mistake.
The temperature inside Officer Carmona TMs patrol car rose to a whopping 143 degrees in just 15 minutes during the demonstration outside the school.
Officer Carmona showed the temperature reading to school parents.
"That's pretty hot... Very hot," Raul Esparza said.
Barker was in shock at the results.
"Wow," she said! "I didn't expect it to be that high."
Jackie Moreno is the parent of a 5-year-old student at the school.
She also has a 4 month old named Joaquin who needs to be buckled up in a car seat in the back of her vehicle at all times.
"It's scary," she said. "I actually did a test once and sat myself in the car with the windows up... To see how long I could last... And it was not even a minute."
With the new school year come changes in daily routines.
Officer Carmona said that's what can often lead to a parent or guardian forgetting to check the back seat of a car.
"That's all it takes is just a few minutes," Ofc. Carmona said.
It's a mistake Barker doesn't want to make.
She knows her children's little lives depend on it.