Get the rowdiest student as a volunteer for an introduction to work.
Stand him or her with their arms outstretched horizontally and place a very large book on each hand. As the student grimaces under the strain you can point out that as usual the student is doing no work at all as the force, in this case the weight of the book, is not being moved any distance. Use the amazing physics timeline from 6500 bc at www.psigate.ac.uknewsitephysics_timeline.html to look at when the idea of work develops . It is interesting to note that thermodynamics develops as a result of the need to understand the new technologies behind the Industrial Revolution. How much easier would thermodynamics be if terms like heat, energy, work, force, power were not used colloquially with different meanings?