Bring in a variety of fruits and vegetables, one for each student. Ideally, you should have several that look somewhat a like. For example, a green apple, a green pear, a green pepper, etc: all items that could be described as round and green.
Warm up by having the students name and discuss the five senses. Tell them that you are going to ask them to use four of their senses, instead of relying on sight as we usually do. Place the fruits & vegetables in an opaque bag. Have all the students close their eyes (or you may blindfold them) and take a piece of fruit from the bag. Without looking at the fruit, the students should examine it carefully. Go around the room and have students describe the scent, texture, taste, etc in detail. When you have finished, ask students to guess what kind of fruit they are holding. Then ask the students to write detailed descriptions of the fruit, but without ever naming the fruit. You may wish to provide them some vocabulary, like peel, rind, stem, pit, etc. Tell them to imagine that they are sending someone to the store to buy the item without knowing what it's called.
When the descriptions are finished, collect them. Collect the fruit and line it up on a table where everyone can see it. I generally arrange it so that similar items are next to each other. Distribute the descriptions, then have students come to the front of the class, read the description aloud and select the correct fruit. Discuss each description and how it did or didn't accurately describe the fruit.
This is an excellent warm-up for writing a descriptive essay, or to help students learn adjectives. I always let the students eat the fruit after the lesson!
Margaret, Chicago, IL