What is a hypothesis? Define an independent variable? Define a dependent variable

The Scientific Method Chapter 1 Section 2

What is the Scientific Method? It is a series of steps used to help solve a problem

Step 1—Make an Observation Pose a Question Define the Problem

Step 2—Form a Hypothesis This is an educated guess as an answer to your problem, based on observations and research. This is a statement about what you think is going to happen Often stated as an “if-then” statement

Step 3—Develop a controlled experiment to test your hypothesis A controlled experiment is an experiment that contains only one experimental variable A variable is the factor that changes in an experiment An experimental variable is the thing being tested Everything else in the experiment or all other variables, must be the same (constants) The experimental group(s) contain the experimental variable. Often a control group is used to compare with your experimental group. A control group is the “normal group” that does not contain the experimental variable

Step 3—Develop a controlled experiment to test your hypothesis g. Independent Variable: The variable that you control (X-axis) Dependent Varible: the variable that you don’t control. It is what you measure (Y-axis)

Step 3—Develop a controlled experiment to test your hypothesis In order to be valid: All experiments must be able to be replicated There must be only one experimental variable. In this way, if there are any questions concerning the results of the experiment, you will be able to show that it was caused by one variable. All experiments should be performed with many trials All experiments have some error, and this should be minimized All experiments must have constants

Step 4 Organize all your data in a table, chart, or graph Types of Data 1. Qualitative data: information that is a characteristic. Ex: smell, color 2. Quantitative data: Information that is usually numeric

Step 5—Analyze the data and come up with a conclusion This supports or negates your hypothesis

EXAMPLES Problem: Is Raid the best insecticide on the market? Research the problem: Look up information on all insecticides Make a hypothesis: Raid is the best insecticide on the market. If it is used, then it will kill insects 30% faster than other insecticides This educated guess was determined by the experimenter based on the research done prior to making this statement

EXAMPLES Develop a controlled experiment: Spray 5 separate plates with equal amounts of different insecticides. Cover each one with the same type of insects to each glass. Place them side by side and time the results Form a conclusion: This is only completed after the data from the experiment has been collected and analyzed. It will either prove or disprove the hypothesis

EXAMPLE 2 Your experiment is testing to see whether plants grow faster in a 40°F or 100°F temperature. What is the experimental variable? Temperature Which group of plants is the experimental group? 40°F and 100°F Which group of plants is the control group? Room temperature Example constants? plant size, plant type, amount of light, amount of water, type of soil

Tools and Procedures Chapter 1 Section 4

Common Measurement System Most scientists us the metric system when collecting data and performing experiments The metric system is a decimal system of measurement whose units are based on certain physical standards and are scaled on multiples of 10

Analyzing Biological Data When scientists collect data, they are often trying to find out whether certain factors changed or remained the same. A graph of the data can make a pattern much easier to recognize and understand

Microscopy Get out your notes from Monday, time to get to work!!!! Microscope Science Magnification is the power to increase an objects apparent size Resolution is the power to show detail clearly. (How crisp and clear it is) Get out your notes from Monday, time to get to work!!!!

Types of Microscopes Light microscopes uses a beam of light passing through one or more lenses. They have a maximum resolving power of 2,000X. Compound light microscopes use two or more lenses to magnify the image a. In order to determine total magnification we must multiply the magnification of each of the lenses. EXAMPLE: 10X ocular (eyepiece) and 40X objective create an image that is 400X the actual specimen (10 x 40 = 400)

Types of Microscopes Electron microscopes can magnify an object up to 2,000,000 X. Two types 1. TEM (transmission electron microscope): Thin section of a specimen is coated with a heavy metal. A beam of electrons are shot at the specimen. This microscope is used to detail the inner ultrastructures of a cell.

Types of Microscopes SEM (Scanning electron microscope): Surface of the specimen is coated with gold. This produces a 3-D picture of the surface of the specimen. Drawback: specimens must be dead