Why is it called a grenhouse?  

Maybe because the stuff in it is usually green?!? I dunno! Never really thought about it!

I am not sure why this is but I always assumed it was because it is a building used to grow plants and plants are always green . You can have colorful plants with pretty little flowers on them but the first color that will strike you when you walk into a greenhouse is the color green .

My guess is that they probably used to be green made with green glass all them years ago! I don't know this for a fact but it's just a guess.... what do you reckon?? :0)

I would first guess toward the obvious of it being used to grow greenery of whatever form.

Alternatively, try not washing it for about 10 years and watch it magically turn green!

I would asume that is because the plants you grown inside them are green,and you are using the glass and the sunlight to grows things without needing to use any other energy. Which makes it enviromentally friendly too.

I may be way off track but I assume that it is because of all the green stuff growing in them. I have never really thought of it before.

Probably for the same reason they call it a 'green thumb'. If you solve that mystery, you'll solve your own. Then you can share the secret with the rest of the class, because I've always thought about that, too. I know after digging around in my garden, my thumb is not green, it's brown.

Your right it is glass, but alot of things inside it are green! I would love to have a green house it has always been a dream of mine!

lol,that's a interesting question,and i think many people even never think about it,like me.
i think one reason is that plants will take in CO2,and so as the places with glass,maybe the two have similar effects,so it is called 'greenhouse' not 'glasshouse'.
if it is called glasshouse,i may think about a house made of glass,and maybe people live in it,lol.