On the bulletin board, create a large picture of a comparison weighing scale (weighing plates on either end) using construction paper. Also, out of construction paper, create several of each of the following:

1. squares, 1/2-squares, 1/4-squares
2. circles, semicircles, 1/3-circles, 1/4-circles
3. triangles, 1/2-triangles, 1/3-triangles

Assign a weight to the "wholes" of the shapes: ie. square=4 lbs., circle=12 lbs., etc. Post the weight assignments as a key on the bulletin board. Create two pockets on the bottom of the board, one to be used to place the shapes in, and the other for a worksheet you compose. Worksheet example:

• Place a triangle, 1/2-circle, and two 1/4-circles on one side of the scale.
• Find three shapes that will equal this amount and place them on the other side of the scale.
• Write down the weights on your worksheet.