Peanut butter sandwich-  Have students write instructions on how to make a peanut butter and jelly sandwich.  Then pick 2 or 3 of them out of a hat to demonstrate in front of the class.  Follow their instructions literally.  If they don't tell you to pick up the knif don't do it.  If they tell you to turn the lid on the jar, but forget to tell you to open it don't open it.  They will quickly pick up what you are trying to teach them.  It is good to give them another chance, but this time give them a definite time limit, because lots of detail is not always a good thing.

Build This Thing- Split the class in half.  One half of the class will look at at simple three dimentional "thing" you have put together for everyday objects around the lab.  It could be as simple as a button hanging from a string on the edge of a ring stand.  Have these students write instructions as to how to build this "thing", and have the other students try to build it from their instructions.

Draw This Thing- This is the same as the activity above except you draw the object instead of building it.