Algebra Balance Scales
Instructions

This virtual manipulative allows you to solve simple linear equations through the use of a balance beam. Unit blocks (representing 1s) and X-boxes (for the unknown, X), are placed on the pans of a balance beam. Once the beam balances to represent the given linear equation, you can choose to perform any arithmetic operation, as long as you DO THE SAME THING TO BOTH SIDES, thus keeping the beam balanced. The goal, of course, is to get a single X-box on one side, with however many unit blocks needed for balance, thus giving the value of X.

Now try the Balance Beam Algebra applet and follow these steps.

Set up the equation 2X + 4 = 8 on the balance beam.

Click on arrows to put 2X + 4 on the left side and 8 on the right side.

It should look like this:

Notice there is a balance.

Click on continue.

The goal is to get just one X on one side and only unit blocks on the other side.

To do this:

• Click on the subtract button.
• Subtract 4 from both sides.
• Notice that 4 unit blocks are removed from both sides and the equation is written in an equivalent, simpler form. (See below)

To solve for X, you divide by 2:

The final equation says that X equals 2 unit blocks.

Click on New Problem to continue.