COLUMBIA, Mo. -

The temperature inside a parked car is much hotter than it is outside. In fact, it can be like an oven. 

Thursday, we bought some refrigerated raw cookie dough, put it on a baking sheet and put it on a car dashboard. 

After a few hours, the cookies were completely baked. When we went outside to check on them, the temperature was 89 degrees outside. Inside the car it was 197 degrees, more than 100 degrees hotter.

This shows why it is important not to leave kids, pets or valuables in your vehicle. So far this year, 23 children in the U.S. have died from heatstroke that were left in cars. The average is about 40 children each year.

Leaving a child unattended in a vehicle is illegal in 20 states including Missouri.