Reminders Pre-Test Unit 1 Exam- Friday 9/2 Last day to turn in ANY Unit 1 Work- Friday 9/2 Assignments turned in for Unit 1: Pre-Test

Introduction to Biology 1.1 Scientific Method

Observations Observations: We use our senses to gather information about the world around us. There are two types of observations.

Qualitative Qualitative observation: (quality) Usually made with our senses. Color, shape, feel, taste, sound. Examples: Olivia is wearing a blue sweater. The lab tabletop is smooth. The dog’s fur is shiny.

Quantitative Quantitative observation: (quantity) Observations that can be measured and given a number. Based on exact measurement. Examples: The room is 8 meters across. Sarah is 141-cm tall. Sam weighs 450 Newtons.

Inferences Inference: A logical interpretation of an event that is based on observations and prior knowledge.

Making Inferences You are at the counter in the office to get a bus pass signed. You see a student leave the principal’s office crying and upset. We could make an inference as to why the student is upset. Could be in trouble (suspended, expelled) Family problems at home (sick, accident) Student not feeling well Student has poor grades (failing, retention)

Steps of the Scientific Method

Experimental Design An Experiment is a set of conditions that allows a scientist to measure the effects of a particular treatment.

Experimental Design The goal of an experiment is to manipulate or change one variable, while keeping all others the same to see what the result is. The first step in experimental design is to figure out what you want to change, and what you think the result of that change might be.

Types of Variables Independent variable: the variable that is being changed by a scientist. Dependent variable: the variable that is being measured as a result of the change. Constant variables: all other variables that stay the same for all trials.

Groups in an Experiment Experimental Group: Control Group: A group that receives the treatment and measures the effect. Ex: I give these plants more water than the other group to see if they will grow taller. A group that receives no treatment and is used for comparison to see if the treatment worked. Ex: I give these plants a standard amount of water.

Other Important Aspects Materials Procedure A bulleted list that includes all of the materials you used in your experiment. A numbered list that details the steps you took to complete the experiment. Remember: you want someone else to be able to conduct the exact same experiment, so every step is important, even if it seems like common knowledge.

Data Collection: Common Measurements i. International System Units Measurement Base Unit Length Mass Volume Time Temperature Meter Gram Liter Seconds Celsius or Kelvin

Characteristics of A Well Designed Experiment Only one significant variable is tested through the experiment. A control group is present. The sample size is large enough to draw a valid conclusion about the hypothesis. Conclusions must be based on measureable quantities or clear criteria. Conclusions are drawn based on data, not on the opinion of the observer (Bias).

Scientific Theory vs. Scientific Law An explanation that applies to a broad range of phenomena that is supported by experimental evidence. A theory explains a series of related phenomena. Example: Cell Theory Evolution Statement that describes some aspect of a phenomenon that is always true. A scientific law relates to a single action. Example: Gravity