The Scientific Method Science is the human effort to understand the natural world and how it works, with observable physical evidence as the basis of that understanding. Vanessa Jason Biology Roots The Power of Observation Science begins with OBSERVATION. How observant are you? On a traffic light, is the green light found on the top, middle or bottom? Bottom! Which hand does Lady Liberty (the Statue of Liberty) carry the torch in? Her right! Why is having a methodical approach to science useful? Why bother with the scientific method? Using a consistent, methodical approach to solving a problem leads to the most accurate results with the fewest mistakes! The scientific method is something all of us use all of the time -- being curious, asking questions, seeking answers – these are basic parts of the scientific method. The Scientific Method is all around us • Fixing a flashlight • Fixing your internet connection • Trying a new recipe for the first time How are we going to solve this one, Bones? Using the scientific method, as we always do, each and every episode. Inference, Hypothesis, Prediction An inference is a logical explanation for something based on prior experiences or knowledge. Example: Grey skies mean rain; sore throats lead to the flu A hypothesis is a possible explanation- it must be testable! Example: Exercising will help me lose weight. Prediction- A prediction is based on your hypothesis. Set up your prediction as an “IF, THEN” statement. Example: If I run 2 miles 5x a week for 6 weeks, then I will lose weight. The Scientific Method The Scientific Method is a series of steps in which a question and/or problem is investigated by observing and experimenting. Step 1 Step 2 State the problem or pose the question. Form a hypothesis (an explanation or possible answer). The Scientific Method Step 3 Test your hypothesis. Experiment! In order to get accurate results from your experiment, it must include two variables and a control group: Independent (manipulated) variable: what is changed during the experiment. Dependent (responding) variable: what you measure during the experiment. Control group- a group that is NOT experimented on; left alone to see what would happen without your manipulations so that you can compare results. Independent vs. Dependent Variables Example- A new mosquito repellent is tested before it hits the market. One arm is sprayed, the other arm is NOT sprayed. After 6 hours, mosquito bites are counted. Independent variable (or manipulated variable)- is what is changed. In this case it is adding the mosquito repellent to your skin. The dependent variable (or responding variable) is what you are measuring- the number of mosquito bites. The control is what you left alone. The control in this example is the arm that is NOT sprayed. Independent vs. Dependent Variables A question might look like this: mosquito repellent effect _________________ # of mosquito bites How does __________________ (independent variable) (responding or dependent) Experimental Group There are two groups in an experiment: the control and the experimental group. The experimental group shows the effect of the variable that was tested. Experiments should be designed to compare the results of the experimental and the control groups. In the mosquito repellent example, which arm serves as the experimental group? The arm with the repellent- it is going to show the effect of the variable (the repellent). The Scientific Method Step 4 Analyze your data. During this step, you’ll want to organize your data by using charts and/or graphs. Types of Data Data can be quantitative or qualitative. Quantitative= numbers (quantity) Qualitative= descriptions (quality) (ex- colors, health, appearance, texture, behavior, etc.) Example: Gummy Bear Lab How much a gummy bear weighs before and after experiment= quantitative data Overall appearance of gummy bear before vs. after experiment= qualitative data The Scientific Method Step 5 Draw conclusions. This is the written portion of your experiment in which you share results and make connections. When drawing conclusions, include if your hypothesis was accepted or rejected. -If hypothesis is rejected (unsupported), then it needs to be modified. -If the hypothesis is accepted (supported), the experiment is typically repeated. Scientific Method in Action Question: Which brand of gum lasts the longest? Trident®, Orbit®, or Eclipse®? Which steps must be taken before designing the experiment? -Collect data -Form a hypothesis How would you design the experiment? Which steps follow the experiment? -Analyze the data -Draw conclusions Design an Experiment! Question: Does fertilizer increase the number of tomatoes on a single tomato plant? Tip: Use a higher number of plants… why? Higher numbers give more accurate results! Possible scenario: 5 tomato plants DO NOT receive fertilizer. Possible scenario: 25 tomato plants receive fertilizer. Should fertilizer be the same amount? Design an Experiment The only difference between the two groups should be the addition of the fertilizer to the experimental group. Everything else should remain the same. Examples Same amount of water Same size pots Why is this important?