I think you might be missing the point of the simple English wikipedia. It's the vocabulary that you use that is simple, not the way in which you express the concepts.
...but equally useful for the example, which is just about dividing rocks into two groups. We're interested in the process of dividing the rocks, not the criteria for division.
They're very different concepts, but for the sake of the example it doesn't matter which you are measuring, you could equally be measuring the number of atoms in each one if you happen to know it.
The Simple English Wikipedia is also for people with different needs. Readers may be students, children, and adults who may find it hard to learn, and people who are trying to learn English. Other people use the Simple English Wikipedia because the simple language helps them understand difficult ideas or topics they do not know about.
i debated this one a lot. on the one hand, people are more likely to recognize the word weight, but on the other hand, weight isn't an inherent property of objects, and (to be overly pedantic) two rocks of equal mass, one at the top of the tower, and one at the bottom, will have difference weights.
