Scientific Terms

What We’re Studying This Year  Science - The various methods in which scientists study the natural world and propose explanations based on the evidence derived from their work; also, the knowledge derived through the process of science.  Biology – The scientific study of living systems and the knowledge acquired from it.

Theory vs. Hypothesis  Theory - a well-established, highly supported by numerous evidences, and highly reliable explanation for scientific phenomena; but may be subject to change as new areas of science and new technologies are developed.  Examples: Gravitational Theory, Cell Theory, Evolutionary Theory, The Big Bang Theory, Germ Theory…  Hypothesis - A testable statement based on observation and inferences that must be capable of being supported or not supported by evidence. A hypothesis is either supported or not supported by the evidence, but never “proven”.  If _(cause)_, then __(effect)__.  Practice!

Is the following statement a hypothesis, a theory, or neither? “Albert Einstein was the greatest scientist in history”.

Bacteria will grow more quickly in a warm environment than a cold environment.

All living things are made up of one or more cells.

If a seed is exposed to acids with a pH less than 4, it will not germinate.

Children who don’t watch TV are smarter than children who do watch TV.

 Experimental Investigation - scientific inquiry investigation in which one or more variables are consciously manipulated and the outcome or effect of that manipulation on other variables is observed.  Experimental designs often make use of controls that provide a measure of variability within a system and a check for sources of error.  The effect of factor X on factor Y: If _(X)_, then _(Y)_.  Involves a hypothesis, a control group and experimental groups, and independent and dependent variables  Independent variable – the variable in the experiment that is manipulated. It is the one variable different among the groups. It is always on the x-axis.  Dependent variable – the variable in the experiment that responds and is dependent on the independent variable. It is affected by changes in the independent variable. It is always graphed on the y-axis.  Controlled Variables (also called constants) – all of the variables that need to be kept the same among the groups so that the only variable affecting the dependent variable is the independent variable.  Control Group - a group that serves as a standard of comparison with another group(s) to which the control group is identical except for one factor. The control group is often the normal or unchanged condition.  Experimental Group – the group(s) in the experiment that has been manipulated to represent the independent variable.

Descriptive vs. Comparative Investigations  Descriptive Investigations – scientific inquiry method that gathers more information about an organism(s) through observational techniques. May or may not involve a hypothesis.  Comparative Investigations – scientific inquiry method that is used to determine and quantify relationships between organisms through observational techniques. May or may not involve a hypothesis.

What can you tell me about this organism?

Observation vs. Inference  Observation – using one or more of the 5 senses to perceive objects or events  Inference – a conclusion made on the based on observations, evidence, and reasoning

Types of Data  Qualitative data – Data without numerical value.  Ex) the plants wilted without water  Quantitative data – can be measured with numerical value.  Ex) the plants lost an average mass of 5 grams without water

DRY MIX – How to tell Independent vs. Dependent Variables  D – dependent variable  R – resulting/responding variable  Y – y axis on graph  M – manipulated variable  I – independent variable  X – x axis

Food BrandRegular (fed for 1 week) New type (fed for 1 week) Weight changeGained 2 poundsGained 4 pounds A crazy cat lady scientist notices her cats are obese, and thinks it might be due to the brand of food she is using. She performs an experiment to find out. Here are the results of his experiment: What is his hypothesis? What are the independent and dependent variables? What could be some controlled variables (factors kept constant between the conditions)? What is the control group? Experimental group? Based on his data is her hypothesis supported? What could be other factors causing the cat to gain weight? What could be the reasoning for the difference in weight gain between the two brands?