Science Assessment

Students are expected to know that:

1. Note: The term “characteristic property” is used to emphasize that these properties are defining attributes that are independent of the amount of the sample, regardless of time, location, size, or shape.
2. The term “substance” means a pure material that is made of the same matter throughout. This is in contrast to the common definition that equates substance with matter that could be made of either a single substance or a mixture of more than one substance. To make this explicit, the phrase “pure substance” is used in assessment items.
3. A substance can be a solid, a liquid, or a gas.
4. Every substance has a set of characteristic properties that are always the same for that substance, regardless of time, location, shape, or size.
5. Furthermore, characteristic properties are consistent throughout a sample of a substance.
6. Characteristic properties with which students should be familiar are boiling point, melting and freezing point, solubility (i.e. how much of the substance can dissolve in water), flammability (i.e. the ease with which a substance will catch on fire), odor, color, and density (i.e., that equal volumes of different substances have different masses).
7. Weight, mass, volume, shape, length/width, texture, and temperature are not characteristic properties of substances and may change.
8. The characteristic properties of a substance do not change when temperature and pressure remain the same.
9. No two substances can have the same set of characteristic properties under the same conditions and that if two materials have even one different characteristic property, they are different substances.
10. The characteristic properties of a given substance result from the types and number of atoms that make up its molecules and the way in which the atoms are arranged into molecules. Two different substances can have the same number of the same types of atoms and still be different substances because of the way the atoms are arranged.

Boundaries:

1. Students are not expected to know that the properties of substance can be different at the nanoscale.
2. They are not expected to know the formula for density (density = mass/volume).
3. Students are not expected to know that the atomic mass of a substance is a characteristic property.
4. They are not expected to know whether specific materials are or are not pure substances.
5. Because some properties do change with changing conditions (e.g., changing atmospheric pressure affects boiling point) all assessment items will make comparisons between substances where it is clear that the conditions, such as temperature and pressure, are constant.