This double pan balance, created for use by participants in the PreK‑2 Algebra E‑Workshop, is a special version of the
Pan Balance - Shapes applet. It uses numbers that are friendly for primary classrooms.
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Each shape is assigned a certain weight. Place shapes on either side of the pan balance by dragging shapes over one of the pans and releasing the mouse button. (To remove a shape from a pan, drag it from the pan and release the mouse button.) The balance will tip to indicate whether the total weight on the left side is less than, equal to, or greater than the total weight on the right side. When the amounts are equal, the result will be shown in the table.
The Count Items button represents the amount in each pan with an algebraic expression. The Show Array button removes the algebraic expressions.
The Reset Balance button removes the shapes from the pans. The Clear Table button removes all data from the table. (When either of these buttons is pressed, the weight assigned to each shape does not change.)
The New Problem button clears the balance, clears the table, and assigns new weights to the shapes.
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Place one red square on the left pan and a blue circle on the right pan. Are they equal in weight? If not, add more red squares to the left pan or more blue circles to the right pan until they balance. Which weighs more, a red square or a blue circle?
- Conduct similar investigations to find out how red squares are related to pink triangles and yellow diamonds.
- Once you think you know the relationships between the shapes, use at least one of each shape and make the pans balance. (You will likely need to use more than one of some shapes.) Don't do this by guessing; try to use logic to figure out how many are needed before placing the shapes on the pans.
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