This isn't philosophy, but I've been having fun with sciencey (sciency?) things.
I just did this little demonstration for my five-year-old: I took a 12ml syringe with no needle attached, and filled it about 15% with hot tap water, turned it tip up, and used the plunger to push out the air. I then plugged the tip of the syringe with my finger, and pulled the plunger back, creating a partial vacuum (obviously, some air leaks back in). The water immediately started to boil, thereby demonstrating that the boiling point of water goes down as air pressure goes down.
Another step one can add (I didn't) is to touch the water that had just been boiling and observe that it's not boiling hot (I guess if one does that with a five-year-old, one accompanies it with warnings that normally water that had just been boiling is hot). A more sophisticated experiment would involve measuring the temperature of the water before and after the boiling, comparing with a control sample in another syringe that hadn't been made to boil, and seeing if the boiling removes thermal energy (as I expect it does).
astronomy club's observatory and got to operate the 24" scope. Here's a quick photo I took of a small portion of the Andromeda Galaxy, showing a large star cloud (big circle) in it, an open cluster (small circle) in it, and a bunch of dark lanes, presumably due to Andromedan dust blocking out the light. The photo is about 17 arcmin on each side.