SC15.8.2

Science (2015) Grade(s): 8

Planning and Carrying out Investigations

Patterns

Students know:

A substance is matter which has a specific composition and specific properties.
Every pure element is a substance. Every pure compound is a substance.
Pure substances have characteristic properties.
Characteristic properties are physical or chemical properties that are not affected by the amount or shape of a substance.
Characteristic properties can be used to identify a pure substance.
Physical properties of a substance are characteristics that can be observed without altering the identity (chemical nature) of the substance.
Color, odor, density, melting temperature, boiling temperature, and solubility are examples of physical properties.
Chemical properties of a substance are characteristics that can be observed but alter the identity (chemical nature) of the substance.
Flammability, reactivity with water, and pH are examples of chemical properties.

Students are able to:

Identify the phenomena under investigation, which includes pure substances and their characteristic properties.
Identify the purpose of the investigation, which includes demonstrating that one pure substance can be distinguished from another based on characteristic properties.
Develop a plan for the investigation individually or collaboratively.
Describe factors used in the investigation including appropriate units (if necessary), independent and dependent variables, controls and number of trials for each experimental condition.
Perform the investigation as prescribed by the plan.
Make a claim, to be supported by evidence, to support or refute an explanation or model for a given phenomenon, including the idea that one pure substance can be distinguished from another based on characteristic properties.
Identify evidence to support the claim from the given materials.
Evaluate the evidence for its necessity and sufficiency for supporting the claim.
Use reasoning to connect the evidence and evaluation to the claim that one pure substance can be distinguished from another based on characteristic properties.

Students understand that:

Each pure substance has characteristic physical and chemical properties (for any bulk quantity under given conditions) that can be used to identify it.
Pure substances can be distinguished from other pure substances based on characteristic properties.
Substances react chemically in characteristic ways. In a chemical process, the atoms that make up the original substances are regrouped into different molecules, and these new substances have different properties from those of the reactants.

Investigation
Claims
Evidence
Substance
Matter
Composition
Property
Element
Compound
Pure substance
Characteristic properties
Physical property (includes, but not limited to, color, odor, density, melting point, boiling point, solubility)
Chemical property (includes, but not limited to, flammability, reactivity with water, pH)