How do you use the scale that was provided. We did equalize the ruler but when you weigh the clay, how can you tell how much it weighs.
The idea is to be able to recreate the same rocket mass each time, so you want to balance 2 (or more) rockets. The scale is the most accurate way to get the masses of clay equal. This removes one variable so that you can try angle and force to get what distance you want each time and reproducible distances.