1. Scientific Method and Experimental Design

2. What is Science?

3. What is Science? What is biology?
Science – an organized way of using evidence to learn about the natural world
Biology – the study of the living world
Skills Used By Scientists:
Observations skills – scientists use their senses (sight, hearing, touch, smell) to observe nature
Hypothesizing skills – scientists attempt to explain observations by forming hypotheses or ideas
Analyzing and Interpreting skills – scientists use prior knowledge and experience to analyze and interpret data collected during experiments

4. How Scientists Work

5. How Scientists Work Using the Scientific Method
State the Problem/Ask a Question
Form a Hypothesis & Make a Prediction
Test Hypothesis with Experiment
Record and Analyze Results
Draw a Conclusion Based on Analysis
Publish and Repeat Investigations

6. Writing Hypotheses & Predictions
Hypothesis – a possible explanation for a set of observations or possible answer to a scientific question
Prediction – a statement, based on the hypothesis that suggests the basic idea for an experiment
Usually an if…, then… statement

7. Writing A Hypothesis Practice
Write a possible hypothesis and prediction for
each of the following observations.
The plants in Mr. Smith’s living room are large, healthy and green but the plants in Mr. Smith’s dining room are small and yellowish in color.
All of the fish in the classroom fish tank are healthy except for the algae eaters that keep dying.
There are only a few un-popped kernels in the popcorn that has been stored in the kitchen but a lot of kernels left in the popcorn that has been stored in the basement.
Can be used as homework or class activity depending on timing. Discuss students’ proposed hypotheses.

8. Designing Controlled Experiments
* Whenever possible, an experiment should be designed to have only ONE variable that is changed at a time. (AKA: Controlled Experiment)
Controlled Variable/s – the variable/s that are purposely kept the same
Manipulated Variable – the ONE variable that is deliberately changed (also called independent)
Responding Variable – the variable that is observed and that changes in response to the manipulated variable (also called dependent)
Experimental Group – the group in which the manipulated variable is changed
Control or Control Group – the group used as a standard for comparison for the experimental group

9. Controlled Experiment Practice
Hypothesis: Tomato plants given fertilizer will produce more tomatoes than plants that are not fertilized.
Plant A Plant B
* Both plants are given the same soil, amount of water and sun, temperature, pot size, and growth time.
* Plant B is fertilized once a week.
What are the controlled variables, the manipulated variable, and the responding variable?
Which is the control and the experimental group?

10. Answers
Controlled Variables – soil, amount of water and sun, temperature, pot size, and growth time
Manipulated Variable – fertilizer
Responding Variable – # of tomatoes
Control – Plant A
Experimental Group – Plant B

11. Why change only one variable?
Plant A
5 hours of sunlight per day
l L of water every 4 days
quart sized pot
30°C for 6 weeks
no fertilization
Plant B
7 hours of sunlight per day
l L of water every 2 days
gallon sized pot
35°C for 9 weeks
fertilized once a week
Can’t tell!
Why did plant B grow more tomatoes?
By only changing one variable, the experimenter can conclude that changes in the responding variable are due only to changes in the one manipulated variable.

12. Collecting & Representing Data
Data - observations and measurements that are made in an experiment
All experimental data must include units. (examples: 9cm, 20sec, 98°C)
Data is often represented using tables and graphs which must be thoroughly labeled.

13. Data Collected from an Experiment
Storage Location Temperature
Inside Room Temp
Inside Freezing Temp
Outside Winter Temp
Percent of germinated seeds 0%
80%
85%

14. Representing Data in Graphs
Storage Temperature Effects on Seed Germination
100 80 60 40 20
Percent of Germinated Seeds (%)
- Inside Room
- Inside Freezing
- Outside Winter
Storage Location Temp

15. Collecting & Representing Data Practice
Using the data below, re-draw the data table and graph to improve them.
Results: Frogs given caffeine jumped 27cm and frogs not given caffeine jumped 20 cm.
Frog not given caffeine
Frog given caffeine
Distance of jump 20 27

16. Frog not given caffeine
Graph needs a label on the X and Y axis and a key.
Table needs units.
Effect of Caffeine on Frog Jumps
Frog not given caffeine
Frog given caffeine
Distance of jump
20cm
27cm
Distance of jump (cm)
Frogs

17. Drawing Conclusions
Conclusion – a final statement that sums up the results of the experiment
Conclusion is based on whether the data supports or refutes the hypothesis.