Scientific Investigation

What is Science?  Something we DO to help us understand the world around us  Evidence-based blend of logic & innovation  Durable BUT can still change!

Steps of a Scientific Investigation 1. Ask a question/identify a problem 2. Observations & inferences 3. Form a hypothesis & make predictions 4. Design & conduct an experiment 5. Collect & analyze results 6. State your conclusion 7. Communicate your results

1. Ask a Question/ ID a problem  Naturally connected to observations Mendel – Why are there so many purple flowers on pea plants? Mendel – Why are there so many purple flowers on pea plants? Why don’t all smokers get lung cancer? Why don’t all smokers get lung cancer? Will studying more at night actually help my test grades? Will studying more at night actually help my test grades? Are energy drinks bad for you? Are energy drinks bad for you?

2. Observations & inferences  Inference – Conclusion based on your observations

3. Formulate a Hypothesis & Make a Prediction  Hypothesis Explanation that might be true Explanation that might be true Can be tested Can be tested Based on what is already known Based on what is already known  Prediction Expected outcome of test, assuming hypothesis is correct Expected outcome of test, assuming hypothesis is correct

UNDERSTANDING CHECK

4. Design & conduct an experiment  Experiment – planned procedure to test a hypothesis  Controlled experiment Experimental group(s) vs. Control group Experimental group(s) vs. Control group Groups are identical except for ONE variable Groups are identical except for ONE variable

4. Design & conduct an experiment  Independent variable – factor that is changed in the experimental groups What you CHANGE between groups What you CHANGE between groups  Dependent variable – what you MEASURE

An example…  Hypothesis – Acidic water harms developing salamander embryos  Prediction – Less salamanders will hatch from eggs in acidic water.  Experiment – Compare salamanders hatched from eggs in acidic water to those in neutral water.

An example…  Independent Variable Amount of acid in the water (High acidity vs. neutral water) Amount of acid in the water (High acidity vs. neutral water)  Dependent Variable # of salamanders hatched from eggs # of salamanders hatched from eggs

UNDERSTANDING CHECK

CONDITIONAMOUNT OF GROWTH Without fertilizer3 cm Fertilizer 18.3 cm Fertilizer 25.1 cm

5. Collect & analyze results  Create a chart and/or graph. CONDITIONAMOUNT OF GROWTH Without fertilizer3 cm Fertilizer 18.3 cm Fertilizer 25.1 cm

6. State your conclusion  Analyze the data. Which fertilizer leads to the most growth? Which fertilizer leads to the most growth? CONDITIONAMOUNT OF GROWTH Without fertilizer3 cm Fertilizer 18.3 cm Fertilizer 25.1 cm

6. State your conclusion  What does this graph tell us?

6. State your conclusion  What’s the most effective flea shampoo? BRAND XBRAND YBRAND Z # of Dogs With Fleas BEFOREAFTERBEFOREAFTERBEFOREAFTER

7. Communicate your results  Identify sources of error. Which data point is probably invalid? Which data point is probably invalid?

Scientific Explanations  Consider the source of the info. Journal vs. newspaper Journal vs. newspaper  Importance of collaboration Working together Working together Peer review & objectivity Peer review & objectivity Must evaluate the work of others to ensure VALIDITY Must evaluate the work of others to ensure VALIDITY

Validity (Is it valid?)  Is it accurate?  Is it reliable?  Does it answer the question it’s supposed to answer?

Scientific Explanations  Scientific theories Accepted because tested & confirmed many times by many people Accepted because tested & confirmed many times by many people BUT no absolute certainty BUT no absolute certainty Example – Earth is flat, etc. Example – Earth is flat, etc.  Laws – generally accepted to be true and universal (gravity)