Hi all. I'm reviewing my daughter's science homework and I disagree with how things are being presented. I wanted some feedback from everyone here to get a sanity check on my own thinking. The exercise is this: answer whether these properties of matter are either an observable property or a measurable property: shape, texture, odor, length, state, sink/float, weight, temperature, magnetic, volume, density, mass. 1. I have a problem with the "or". If we cannot observe a property, how could we ever measure it? The act of measuring requires observation. I can observe whether something's solid, but I can also measure it according to different criteria (e.g., the rate of molecular translation, etc.); I can observe something's texture, but I can also measure it (usually via lasers these days); etc. 2. sink/float: these are actions: verbs, not nouns or adjectives. How can these be properties? Density is a property, but sink/float depends on the density compared to that of the fluid it's in (among other things). It's like asking if sit/run or ascend/descend are observable properties or measurable properties. They are actions to be observed or measured, but not properties of the matter itself. 3. weight: weight is a force, not a property of matter. That is, changing the curvature of spacetime in which a mass resides changes its weight accordingly without any change to the mass itself (although the consequence of the modified force might change the mass). No? 4. more generally, isn't any observable property also measurable? If we can observe it, we can visually measure it, even if this form of measurement is highly imprecise. It seems to me "observable" and "measurable" are not mutually exclusive. This seems like a poor exercise to teach scientific concepts: am I crazy and/or ignorant (NOT mutually exclusive)? Thanks for any opinions.