Qualitative Observation

A qualitative observation uses your 5 senses and includes descriptions of sights, sounds, smells, and textures.

Quantitative Observation

• Quantitative observations are expressed as numbers.

Inference

• An inference is a logical conclusion drawn from available evidence and prior knowledge.

Hypothesis

• A hypothesis is an educated guess to a problem, which is written in a certain way that leads to further investigation.

• If… then… because…

• Independent variable comes after the word if

• Dependent variable comes after the word then

Independent Variable

• The independent variable is the factor that you wish to test. It is what you change.

Dependent Variable

• The dependent variable is the factor that you measure to gather results.

Write a hypothesis for the following problem:

• "Do small pieces of ice melt in a shorter time than a whole ice cube if they are both exposed to room temperature air?"

Example Hypothesis:

• If a whole ice cube and a small piece of ice are exposed to room temperature air, then the small piece of ice will melt faster, because it has less surface area.

Constants

• Constants are all of the factors that must be identical across all groups you are comparing.

• Constants often include such factors as amounts, temperatures, measurement tools and materials.

An investigation:

• A group of students investigated bacterial levels in different areas of their school. Using moistened cotton balls, they wiped an 8cm length along each surface they tested. Then they wiped each cotton ball across a culture medium in a Petri dish. After three days, they measured the size and number of bacterial colonies that grew in each Petri dish.

Variables and Constants

• Independent Variable: Locations in the school• Dependent Variable: size and number of

bacterial colonies• Constant: type of cotton balls, size of surface

tested, type of medium in Petri dishes, days incubated