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.

  • 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.

  • The chair has 4 strong legs.
  • Blue skies are pretty.
  • T. rex was a vicious killer.


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

  • units are g/cm3

YouTube video showing how density changes as you change the density of a pillow.

Speed Link



Parental Contact Form

Topics For Student Lessons


Special FX Permission

Course Outline

Research Paper

Practicing Measurement Skills

Graphing and Density 1

Graphing and Density 2

Density Worksheet

Excel data for sunspot lab

Percent Deviation




Direct relationship- as x gets bigger, y gets bigger. For example, the relation ship between age and size (until maturity) is a direct relationship.

Inverse- as x gets bigger, y gets smaller. For example, the relationship between time spent at the mall and the amount of money in your pocket is an inverse relationship.

Cyclic- a repeating pattern. Most relationships in Earth Science are cyclic.

  • the repeating high and low tides
  • temperatures go from cold to warm each day
  • temperatures go from cold to warm each year
  • the phases of the moon are cyclic

Independent- x has no effect on y. This will be a straight, horizontal line and it means that one variable has no effect on the other.

Percent Deviation (or "percent error") describes how wrong a measurment is.


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