I Believe Common Sense Is No Longer Common

What happened to common sense?
I literally just had the following conversation with my daughter who was running herself a bath (bearing in mind it's not the first time she has ran herself a bath):

Her (in a pouty voice): My bath's cold and I can't get the water any hotter
Me: is the cold tap running?
Her: a bit, yeah
Me (thinking): well, that might be your first clue....

Sometimes I weep for humanity when people can't work out that cold water makes things cold (or at least colder).