Concept first, then words. My students know nothing but that "the area under the force-position graph" means something. We figured out the relationship between the force of a spring and the compression or stretch of that spring. Then we tried to launch two cars so that, after the spring returned to its natural length, the two cars would be going the same speed. (Check out Kelly O'Shea's blog entry at http://bit.ly/1iVtpJC). Then we use this model to figure out how different areas of the force-position graph mean--as in, if a car starts at rest, what will its final velocity be given a certain area of the force-position graph? Again, Kelly O'Shea: http://bit.ly/1F6Zloz). And, we ended the day with three equations, all of which equal the area under the force-position graph. What does it mean? That's Monday. Have a great weekend, everybody!