Hello, Part 1: I've done some reading recently and found that Ibs is actually .435 kilograms equal to pound mass. This is the Pound mass definition but people seem to always argue that Ibs is measuring weight not mass... There is a difference between ibf and ibm. It's my understanding that the scales we use only measure force with a conversion to mass. Part 2: I always imagined a scale measuring the force downward since the spring is brought downward or pressure plates. I recently learned that the scale is measuring normal force which I know is in the opposite direction. I've done some thoughts on this and I know that downward is negative and we don't write out our mass as a negative number. Also, you experience the normal force which the scales exerts on to you. You exert the force on the scale. Is this how I should think about it?