As Scouts arrive, pair them up and invite them to play Dots and Boxes. The rules are printed on each page.
Have your Den Chief or Denner lead an opening ceremony where the U.S. Flag is presented and the Pledge of Allegiance is recited. Then have them lead the den in saying the Law of the Pack.
Discuss (and demonstrate) how pulleys (i.e., block and tackle) can make it easier to move heavy objects.
(Review the explanation at this website for assistance http://www.howstuffworks.com/pulley.htm )
Use the inexpensive pulleys, cord, 'S' hooks, and small boards that you prepared before the meeting to illustrate the various pully configurations. Let the boys help set up the pulleys and pull the ropes to see how easy it is to lift the load.
To avoid holding the board that supports the pulleys, you can place it between the backs of two chairs.
To help them understand how the pully is working, show that with N ropes sharing an equal portion of the load you only have to pull with 1/Nth of the effort. But also show that to lift the load 1 inch with N ropes each rope has to move 1 inch which means that the end of the rope has to move N inches. Make sure they understand the trade-off between lifting effort and distance.
Have the den select a denner and assistant denner. Make sure that the members of the den understand that this is a short term appointment and that other members of the den will get a chance to be denner or assistant denner. Also make sure that they understand that this is not a 'figure head' position - there are real responsibilities (such as helping to prepare for meetings and helping to clean up afterwards.)
Have a short ceremony where you present the denner and assistant denner cords.
As each Webelos Scout leaves the room, have him salute the Den Leader using the proper Cub Scout salute and have the den leader return the salute.