8th Grade Earth Science

Learning Target: What is the Scientific Method?

What does the Scientific Method mean? Why is it useful? Do Now What does the Scientific Method mean? Why is it useful?

The Scientific Method is a series of organized steps that guide an investigation Observations / Questions/State a Problem Research/Gather backgroud knowledge. Construct Hypothesis Design and Conduct an Experiment Interpret Data (gather and analyze data) Draw Conclusions BrainPoP!

1. Posing Questions Scientific questions can come from observations, or from curiosity. A scientific question is precise, and can be answered through observation, measurement, testing, or analysis. Ex: Do plants grow better in sunlight or in darkness? Do plants grow taller in white light or green light? What is lightening?

2. Developing a Hypothesis A hypothesis can be: a possible explanation for a set of observations or an answer to a scientific question Ben Franklin (1700s) observed that lightening and electrical sparks both had bright white light, zigzag pattern, and made a crackling noise. So he came up with the hypothesis that lightening is a type of electricity.

Observation Scientific Question Hypothesis Ice cubes float in a glass of water. Why does ice float in liquid water? Water in the solid phases (ice) is less dense than liquid water. Moss grows only in the shaded area of a patio. Does moss grow better in shade or direct sunlight? Direct sunlight prevents moss growth. Tomato plants grown near pine trees are taller than those grown near broad-leaf trees. Do tomato plants grow taller in acidic soils? Tomato plants grown in acidic soils are taller than those grown in basic soils.

3. Designing an Experiment An experiment is a procedure designed to test a hypothesis. Controlled Experiment: conditions are established by a scientist A variable is any factor that can affect the results of an experiment. 1. Independent Variable (manipulated) – controlled by the scientist. 2. Dependent Variable (responding) – what is being measured in the experiment. Ben Franklin’s expt is NOT controlled. Dependent – changes in response to the independent variable.

Question Independent Variable Dependent Variable How does salt affect water’s freezing point? Amount of salt in the water Freezing temperature Which fertilizer grows the largest apples? Type of fertilizer Size of the apples What size parachute slows a free fall fastest? Size of parachute Speed of the free fall

Experiments have a control group and an experimental group: Control group: represents the norm and shows what would happen if the independent variable were not manipulated by the scientist. Experimental group: has conditions identical to the control group, EXCEPT for the variable being studied. **Only change ONE independent variable at a time!

4. Collecting & Interpreting Data Data are the facts, figures, and any evidence gathered through observations. In order to interpret data, it can be helpful to put it in a table or to plot it on graph. Ben Franklin’s expt is NOT controlled. Dependent – changes in response to the independent variable.

5. Drawing Conclusions After you have collected and interpreted your data, and you can draw a conclusion about your experiment. Did your data show that your hypothesis was correct? Scientists may want to repeat your experiment to determine if its results are correct. Results can suggest new questions can lead to new experiments. Ben Franklin’s decided that lightening behaved exactly as electricity did in his other experiments – correct hypothesis.