In secondary school here they used demonstrate the explosive nature of the mix of oxygen and hydrogen.
A plastic chemical bottle was placed upside down on a tripod same as used with a Bunsen burner,minus the wire/asbestos mesh. The raw materials ,peroxide and something(cant remember) else were mixed in a conical flash , A small lenght of pipe was used to fill the bottle with hydrogen ,then a lighted match was placed just under the mouth of the bottle , the bottle took off like a rocket accompanied by a loud bang.
There was a buddy of mine in school around that time ,he sneaked into the chemical stores at the back of the science class rooms ,relieved them of an oil filled flask with hunks of sodium in it , we ended up making what we called depth charges from it ,hack some holes into the lid of a glass jar ,place some stones in there for weight ,then a chunk of the featherweight metal ,put the lid on ,toss it into the river or pond ,boom just like in those old war movies .
Hilti blanks from nail driving guns were another thing we would find around building sites as kids ,I had a few smarts under my belt due to guidance about such things from my Dad particularly ,other kids werent as carefull and throwing these blanks on the fire was seen as 'great craic' altogether. There was one kid in my class who thought it would be clever to try and hammer a nail into the squinged end of the hilti shell ,damn thing went off and give him a quick painfull lesson ,lucky though the damage was only superficial. I ended up caught with a few strips of the blanks by my dad at one point ,there was a full military style enquirey into the who's where's and what's of the situation ,anyway luckily my dad saw that the things were disposed of in the appropriate manner , and took the time to reitterate safety precautions when dealing with dangerous things like that . Lesson learned and in good time too .Bit of a treat drift ,but I guess it sits in well with Johns previous post .