Today... Turn in your paper airplane lab, if you didn’t finish last class period. Go get your science notebook. Scientific Method Quiz is scheduled for Friday 9/18!

Scientific Method Biology

Science is… Knowledge of the physical world that is gained through observation and experimentation

Scientific Method 1.Testable Question 2.Observations/Inferences 3.Write a hypothesis 4.Conduct the investigation 5.Record data and Making a Graph 6.Draw conclusions and share results

1. Testable Question

This is the reason you are doing the experiment – you want to answer this question by the end of your experiment! CANNOT be based on opinion!

1. Testable Question Examples of NON testable questions: Are dogs better than cats? Is the cafeteria food good? Do roses smell good?

1. Testable Question Examples of GOOD testable questions: Does the amount of sunlight a plant get affect how it grows? Which disinfectant works the best on household germs?

1. Testable Question “What is the effect of IV on DV?”

Variables in an Investigation Independent Variable (IV): Dependent Variable (DV): Constant: Variable being manipulated Variable being measured Variables that are held the same in an investigation

Identify the following for each of the following testable ?’s: IV, DV, 2 possible constants 1.What is the effect of the amount of sunlight a plant gets on the growth of the plant? 2.What is the effect of amount of disinfectant on the amount of household germs?

IV DV Cut Outs Changing the Independent Variable... Causes the change in the... Dependent Variable The dependent variable depends on the independent variable X is always the IV (x is the input) Y is always the dependent variable (y is the output) What you get out depends on what you put in

IV DV Matching

2. Making observations/inferen ces

Observations Any information collected with your senses in an observation Sight, smell, touch, hear, taste This is not opinion, but factual

Observations Data can be … Quantitative – measurable 3 meters 4 marbles 35 degrees Celsius Qualitative – describable Red flowers Tastes bitter Smells like cookies

Inferences Using your observations to make a guess about an outcome/conclusion This can be scientific opinion!

Practice Observations: I hear people screaming I smell cotton candy, popcorn, and hamburgers I see a lot of people Inference = ?

Look at these two sets of animal track List 2 OBSERVATIONS Make an INFERENCE

Now what do you think? Make an INFERENCE Make 1 OBSERVATION

Now what do you think? Make an INFERENCE Make 1 OBSERVATION

3. Write a hypothesis

3. Writing a Hypothesis A hypothesis is a TESTABLE “educated guess” about the outcome of your experiment Using your observations/inferences… “ If IV…, then DV….”

Write a hypothesis for the two following testable questions: 1.What is the effect of the amount of sunlight a plant gets on the growth of the plant? 2.What is the effect of amount of disinfectant on the amount of household germs?

3. Writing a Hypothesis Is everyone’ hypotheses going to the exact same? Is it okay if your hypothesis ends up being wrong?

4. Conducting the Investigation

Designing a Controlled Experiment A controlled experiment works with one variable at a time. If several variables were changed at the same time, the scientist would not know which variable was responsible for the observed results. An experiment is based on the comparison between a ____________ with an ________________. control group experimental group a) These two groups are identical except for one factor. b) The control group serves as the comparison. c) The experimental group shows the effect of the variable that is being tested.

4. Conduction the Investigation Control Group vs. - “Normal” group -Does not receive the IV change -Serves as the comparison. Experimental Group - Does receive the IV change - Shows the effect of the variable that is being tested.

What are possible control groups for the following? 1.What is the effect of the amount of sunlight a plant gets on the growth of the plant? 2.What is the effect of amount of disinfectant on the amount of household germs?

Identifying Variables Worksheet

Bellwork (Sept 10, 2015) In order to test the effectiveness of a new vaccine, 50 volunteers are selected and divided into two groups. One group will be the given a sugar pill as a placebo & the other will be given the vaccine. Both groups are given a pill is identical in size, shape, color and texture. 1.What is the Independent Variable? 2.What variables are constants in this experiment? 3.Describe the control group. 4.Describe the experimental group. *** After you finish the bellwork, get out the assignment (Identifying Variables Wkst) from last class period & work on it!

4. Conduction the Investigation Procedure... List of steps followed to complete an experiment (directions) 1, 2, 3... order (not a paragraph) DETAILS!

4. Conduction the Investigation Writing a procedure 1.How is the IV changed? 2.How is the DV measured? 3.What needs to be held constant throughout the experiment?

Writing a Procedure: What is the effect of amount of disinfectant on the amount of household germs?

Writing a Procedure: What is the effect of the amount of sunlight a plant gets on the growth of the plant? 1.Gather 3 pea plants that have sprouted and are 5 cmin height. Place 1 plant under a sun lamp that will be on 24 hours a day, 1 for 12 hours a day, and 1 for 0 hours a day. 2.After 7 days, measure the height of each plant in cm with a ruler. Record data in a data table and continue for a total of 4 weeks. 3.All plants should be planted in normal soil with no fertilizer and watered daily.

Procedure Writing Activity

Bellwork 9/11 Bailee wanted to see if the color of light would affect the growth of a plant. 1.Identify the Independent Variable 2.Identify the Dependent Variable 3.Describe the control group? 4.List THREE constants

5. Record Data and Making a Graph

Data Tables: place for data that is collected during the experiment to go Graph: visual representation of data Bar graph: amounts Line graphs: change over time

5. Record Data and Making a Graph Single Line Graph Title: The Effect of IV on DV DV (units) IV (units)

5. Record Data and Making a Graph Title: The Effect of IV on DV IV (units) DV (units) Units on x and y- axis need to have the same number scale that it goes up by!

Collect and Analyze Results Multi-Line Graph The Effect of IV on DV DV (units) Time (units) KEY: (IV changes)

What is the effect of the amount of sunlight a plant gets on the growth of the plant? Height (in) 0 hrs/day12 hrs/day24 hrs/day WeekPlant 1Plant 2Plant

Number of Leaves Remaining on Tree During Fall Tree 1Tree 2Tree 3 Week Week Week Week Week

6. Drawing and Sharing Conclusions

Step 5: Drawing Conclusions The evidence from the experiment is used to determine if the hypothesis is proven or disproven. Experiments must be repeated over and over. When repeated, the results should always be the same before a valid conclusion can be reached.

You want to determine the effects of a certain fertilizer on the growth of orchids grown in a greenhouse. Materials that are available to you include: greenhouse, 100 orchid plants, water, fertilizer, and soil. You want to know if the orchids will grow best with a weak concentration of fertilizer, a medium concentration of fertilizer, or a high concentration of fertilizer. How will you design an experiment to test different concentrations of this fertilizer? State your hypothesis: Possible answer: I predict that the orchids will grow best with a medium concentration of fertilizer.

Here is one possibility: The 100 plants will be divided into 4 groups as follows: The plants will be watered daily. Over a period of a month, the plants will be measured to see which ones grew the tallest. Group 1: 25 plants will receive plain water. Group 2: 25 plants will receive a weak concentration of fertilizer. Group 3: 25 plants will receive a medium concentration of fertilizer. Group 4: 25 plants will receive a high concentration of fertilizer.

Control GroupExperimental Group What is the control group in this experiment? The control group consists of the 25 plants that are receiving plain water. What is the experimental group in this experiment? The experimental group consists of the 75 plants that are receiving various concentrations of fertilizer.

In a “controlled experiment”, all variables must be kept constant except the one variable that is being changed. What variables must be kept constant in this experiment? All plants must receive the same amount of fluid each day. All plants are grown in pots of equal size. All plants are grown at the same temperature. All plants receive the same amount of sunlight. What variable is being changed in this experiment? The variable being changed is the amount of fertilizer received by each group of plants. What variable is being changed in this experiment? The variable being changed is the amount of fertilizer received by each group of plants.

Group 1 (Control Group): Grew to an average height of 15 cm. Group 2 (Weak conc.): Grew to an average height of 35 cm. Group 3 (Medium conc.): Grew to an average height of 28 cm. Group 4 (High conc.): Grew to an average height of 10 cm. Is your hypothesis supported or disproved by these results? We hypothesized that the orchids would grow best with a medium concentration of fertilizer. The results do not support this. The results disprove our hypothesis.

Group 1 (Control Group): Grew to an average height of 15 cm. Group 2 (Weak conc.): Grew to an average height of 35 cm. Group 3 (Medium conc.): Grew to an average height of 28 cm. Group 4 (High conc.): Grew to an average height of 10 cm. What is your conclusion based on these results?  Orchids grow best with a weak concentration of fertilizer.  At medium to high concentrations, plant growth is inhibited.

Analysis Questions Why is it important to repeat the experiment many times? Experiments should be repeated to see if the same results are obtained each time. This gives validity to the test results.

Analysis Questions What is the importance of the control? The control shows what will happen when the experimental factor is omitted. Without the control, there would be no basis for comparison and you would not know how the experimental factor affected the results.

Analysis Questions Why is it so important that a scientist accurately describes the procedure used in the experiment? It allows other scientists to repeat the experiment and verify the results.

Analysis Questions In a “controlled experiment”, why must all of the variables, except one, be kept constant throughout the experiment? If several variables were changed at the same time, the scientist would not know which variable was responsible for the observed results.

Experimental Design Practice

Exploring the Scientific Method Virtual Lab