"Metal" is pretty vague, it could mean everything from oil rubbed bronze to brushed steel to 22 karat yellow gold leaf and even rusted copper. It seems that your instructor wants you to demonstrate knowledge of both procedural and bitmap texturing. Variety seems to be preferred so I hope all metals wouldn't pose a problem.
Maybe model a few leaves and a flower pot. They could provide an opportunity to create different materials and help get convey it is a flower. I don't know how familiar you are with common material properties like color/reflectivity/bump etc or lighting in general (the two go hand in hand), if you're not, explaining them will make this reply into a mini novel. Lots of free tuts around to get you started so we could have something to go on. As a general rule, shiny metals have dark color/diffuse values and the reflection color is what would make bronze look different than say chrome. Also, look at references and do it often.
Last edited by Gen; 18-11-2015 at 12:20 AM.