So you open the freezer, get out some ice cream, and close the door. That’s easy. Then you open the door again to put the ice back, and it’s harder to open!
The science is easy. When you open it the first time the cold air falls out, and warm, lighter air flows in. When you close the door that thin warm air starts to contract. The outside air is pushing the door closed, with more pressure. It will stay that way until the pressures equalize.
You can try it again and again, but don’t forget to eat some ice cream each time. Sort of like a drinking game but for the sedentary and mature.
Robert Krampf has lots of these on his website. You can sign up for his free weekly take-home experiment, or for a small fee you can subscribe to the entire access, videos and all. http://thehappyscientist.com/