Doors are easy to kick in...unless you have one of these bad boys. We use the Nightlock in the Lovell household and I highly recommend it. Further reading: https://warriorpoetsociety.us/nightlock-door-brace/

Nightlock Security Barricade - http://amzn.to/2CVvSC8

Warrior Poet Store - https://warriorpoetsociety.us/store/