Observations and Inferences

Topic 1: Introduction to Earth Changing Environment

What is an observation?

An observation is gathering information using your senses.

What is an inference?

• An inference is an interpretation of an observation.

Give an example of an inference based on the following observation: a girl received a 100% on the test.

~She studied~She’s smart~She’s good in that subject~She’s going to put the test on the refrigerator

What is a system of classification?

A classification system is grouping together items according to their same characteristics (observations and inferences)

Why are objects classified?

• Objects are grouped together to make the study of objects more meaningful or easier to understand

• Quicker access• More useful

What is a measurement?

A numerical value for an aspect of an object which allows for a more accurate observation.

What is mass?

Mass is the amount of matter in an object

The instruments typically used are an electronic scale or a triple beam balance

What is volume?

Volume is the amount of space that a particular object takes up. This object

can be solid, liquid or gasses

How do we determine the volume of a regular object?

We can determine the volume of a regular shaped object by measuring the length, width and height.

Use the formula Volume(V) = Length x Width x Height

How do you determine the volume of an irregularly shaped object?

To determine the volume of an irregular shaped object use the process know as water displacement. Water displacement is the change of water level on a graduated cylinder.

1st: Measure the original water level

2nd: Drop the object in the graduated cylinder

3rd: Record the final water level

4th: Subtract the original water level from the final water level.

What is the formula for percet deviation?

Percent Deviation is how much away your answer is away from the real one.

A low % deviation is when your value is closer to the real one (accepted value)

**(measured – accepted)**

% Deviation = difference from the accepted value x 100

accepted value

Solve the following problem:

A student measures the mass of an object to be 25g and the accepted value is 20g. What is the percent deviation?

% Deviation = 25g – 20g x 10020 g

% Deviation = 5g x 100 20g

% Deviation = .25 x 100 = 25%