No scale is needed to determine the weight of a sample in grams. A metric unit for measuring the mass of objects, grams are often used in science experiments. When you do not have a scale, you can make a balance scale from a ruler and use coins from your pocket to find the weight. This handy project makes science experiments at home simpler without having to spend money on an expensive scientific scale or balance beam.

Step 1. Place the pencil under the 6-inch mark on the ruler with the pencil perpendicular to the ruler.

Step 2. Tape each of the two squares of cardboard to the ends of the ruler so the ruler maintains its balance on the pencil without tipping one direction or the other.

Step 3. Place the item you want to weigh on one of the two pieces of cardboard, causing the ruler to tip to that side.

Step 4. Stack coins on the other cardboard until the ruler returns to balance. If you add a coin and the balance tips too far to the coins side, replace a larger coin with a smaller one.

Step 5. Add the weights of the coins placed on the balance to find the weight in grams of the item. Use 2.5 grams for each penny, 2.3 grams per dime, 5.0 grams per nickel and 5.7 grams per quarter.