This is a picture of a lever. Levers are a lot like the see saws you play on in the park. One thing levers help us do is lift heavy objects that we couldn't lift on our own.http://www.google.com/imgres?imgurl=http://ffden-2.phys.uaf.edu/104_2012_web_projects/kjersten_williams/first_class_lever.gif&imgrefurl=http://ffden-2.phys.uaf.edu/104_2012_web_projects/kjersten_williams/Page_3_Physics_of_Chewing.html&h=175&w=225&tbnid=E2wGd0uXjFPT3M:&zoom=1&docid=wJJqGa-AZWphYM&ei=9B9EVZy9H5CDNq_XgKAM&tbm=isch&ved=0CDoQMygMMAw

A machine   is something that helps us do work .  Work means pushing or pulling in order to move an object.  A machine can be just one piece or it can have many different parts.