fire hydrant pee post for puppy!?!?
Invest in a bike specific beanie or hat. They are made very thin so they fit under a bike helmet without too much difficulty. You just need to widen the restraint system a little. There are lots of different options from skintight skullcaps to fleece that is a little thicker. They can either come down over the ears like a normal winter hat or have special extensions that reach down just to cover the ears. Take a look at the clothing at Performance Bike for options. Also, be sure to go to your local bike shop since your son would probably rather try some hats on with a helmet to see how it feels. Another possible cool/cold weather option is a vest. I don't know how far the ride is or how cold it gets where you are but a cycling specific vest is made of a thin windbreaking material that helps keep your core warm without adding bulk. They often also have reflective material on them to make the rider easier for cars to see. Hope that helps.
Some hard-wired smoke detectors have battery back-up, others do not. If you have just one that has a battery back-up and the battery in it goes dead, by design all the detectors will chirp. You can either change the battery or go buy non-battery back up detectors to replace the ones with batteries. I just went through this over the weekend : )