Here is a field project that students always like. Have students (you might have only one or a few students do this as a special or alternative assignment) print a collection of brand/product symbols (an alternative would be to have students create a PowerPoint presentation with images inserted to be projected in the classroom for all to see). Then have this student quiz fellow classmates to see if they can recognize the product or company. This will show students how effective symbols are and how much involuntary learning has taken place in their life. You might give a reward to the student who had the most correct responses.