13 yr olds take you literally. Remember that. If you tell them to drop something in the crock pot, they will DROP it in...even if it's 6 lbs of frozen roast. 6 lbs of roast + a ceramic crock pot liner = disaster
When you can see through the bottom of your crock pot
and the interior of the heating portion looks like this
it is time to change your cooking plans and to go shopping for a new crockpot.