Observation: Any fact or data that is obtained by using one of the five senses. Observations are impartial. Note: measuring something is an observation by comparing to a standard.
ex.:
- A chair has 4 legs.
- The sky is blue.
- The first sound is louder than the second.
Inference: An opinion, conclusion, or prediction based on data.
ex.:
- The chair has 4 strong legs.
- Blue skies are pretty.
- T. rex was a vicious killer.
Measurements
Length is measured with a meter stick and has units of meters, centimeters or millimeters.
Area is length x width and the units are cm2.
Volume (units are cm3 for solids and mL for liquids)
- for a regular solid: length x width x height
- for an irregular solid use the water displacement method: immerse object in a graduated cylinder and note the amount of water rise
Mass measures the amount of matter in an object.
- units are grams and is measured with a balance
Density measures the amount of matter that is crammed into an object.
density = mass/volume
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