1. Scientific Investigation, Variables, and Graphs
Van Roekel 2016

2. BILL (DO NOW)
Pass up syllabus and science safety contracts in that order.
Complete the science safety test.
You may work with a partner.
We will grade this for correctness after 10 minutes.

3. Science and Human Values
In what ways has science changed the way we live our lives?
What benefits has there been due to scientific breakthroughs?
It is important that everyone understand what science is, what it can do, and what you can do

4. What is Science? Goal of science –
to investigate and understand the natural world
to explain events in the natural world
to use those explanations to make useful predictions

5. How Scientists Work The Scientific Method Make Observations
Test Hypothesis (Experiment)
Asking Questions
Analyze Data and Conclude
Do Research
Communicate Results
Form Hypothesis

6. Thinking Like a Scientists
Research usually begins with observations
Observation: The process of gathering information about events or processes in a careful, orderly way
Information gathered from observations is called data
Data is used to make inferences
Inference: A logical interpretation based on prior knowledge or experience
After initial observations, one or more hypotheses will be proposed
Hypothesis: A proposed scientific explanation for a set of observations

7. For each of the following statements tell whether it is an observation or an inference.
Grape juice causes stains on white carpets.
When grape juice is spilled on white carpet, a purple color appears on the fabric. The purple color is not removed by normal laundering.
The height of a plant is 21.3 cm.
Plant food makes plants grow taller.
A chemical reaction produces 5.1 mL of carbon dioxide in 3 minutes at 20 C
A chemical reaction produces 2.6 mL of carbon dioxide in 3 minutes at 15 C
Heat speed up chemical reactions.
Pollution causes global warming.
Inference
Observation
Observation
Inference
Observation
Observation
Inference
Inference

8. Types of Observations
Observations are made before, during, and after an experiment. There are two main types of observations used by scientists.
Quantitative – information that can be measured and written down with numbers. Examples include data such as height of plants, mass of an object, and length of cells.
Qualitative – information that can’t actually measured, but can still be observed. Examples include data such as flower color, bubbles from gas production, and the texture of a frog’s skin.

9. BILL
Distinguish (Compare) the following terms and give an example of each:
Observation vs. Inference
Qualitative vs. Quantitative.
Observation: The process of gathering information about events or processes in a careful, orderly way.
Example: The height of a plant is 21.3 cm.
Inference: A logical interpretation based on prior knowledge or experience
Example: Plant food makes plants grow taller.
Quantitative: information that can be measured and written down with numbers
The length of a cell is 25 micrometers
Qualitative: information that can’t actually measured, but can still be observed.
The flowers had a mixture of red and yellow petals

10. Experiments – Variables
An controlled experiment in which only one variable is changed at a time, while all other variables are kept unchanged, or controlled
Independent variable (manipulated variable): The variable that is deliberately changed by the experimenter.
Dependent variable (responding variable): The variable that is observed and that changes in response to the independent variable
Constant Variable(s): variables that are constant and unchanged throughout the experiment.
A control variable strongly influences values; it is held constant to test the relative impact of independent variables

11. Identify the independent and dependent variables for each of the scenarios below.
Mary wants to know whether plants grow more leaves in red, green, or blue light.
Independent Variable: Type of light. Dependent Variable: Amount of leaves on each plant
Tom wonders whether the speed of his model trains affects the time it takes the train to stop.
Independent Variable: Speed of Model Train Dependent Variable: Time it takes to stop
Christine is studying the pressure in a closed container at different temperatures.
Independent Variable: Temperature Dependent Variable: Pressure in closed container
John is trying to determine is basketball players have lower blood pressure than people who don't play basketball.
Independent Variable: Basketball player or not Dependent Variable: Blood pressure
Janet is doing an experiment to see if the number of peanuts per plant changes when the amount of fertilizer given to each plant is changed.
Independent Variable: Amount of fertilizer Dependent Variable: Amount of peanuts per plant
Theresa wants to see if different brands of yeast makes her loaves of bread rise to different heights.
Independent Variable: Different brands of yeast Dependent Variable: Amount bread rises.

12. Experiment - Groups
Control Group – is the group in an experiment or study that is not changed in any way and is used as a benchmark to measure how the other tested subjects do.
Experimental Group – the group in an experiment in which the independent variable is altered. The experimental group is compared to a control group.

13. For each of the following experiments determine what will be the control group and what will be the experimental group.
A marketing group wants to test whether a fertilizer company's claim that plants grow taller with their fertilizer is accurate. Forty seedlings of the same plant are planted at approximately the same height, in the same type of soil, and at the same time. Twenty of the plants receive the recommended amount of fertilizer at each watering. The remaining twenty plants receive the same amount of water with no fertilizer. All forty plants are grown at 25 C and receive 10 hours of light daily. The height of each plant is recorded every 5 days for two months.
Control Group: Plants that receive no fertilizer Experimental Group: Plants the receive fertilizer
An toy company wanted to know if giving their employees an extra 30 minutes during their lunch break would increase productivity. 20 employees with similar experience, education, and training were divided into two groups. 10 employees were given their regular 30 minute lunch break, while the other 10 were given an hour long lunch break. The amount of toys each group produced was measured on a daily basis for a month.
Control Group: Employees w/30 minute lunch Experiemental Group: Employees w/hour lunch

14. Sharing your data (Graphing)
Graphing is used by scientist to display data that is collected during a controlled experiment.
In Biology we will typically use line graphs to show change over time, or bar graphs to show comparisons.
All Graphs should contain 5 major parts:
Title – shows what the graph is about. It should be a concise statement placed above the graph that gives the reader an idea about the graph.
Independent Variable – this variable should be placed on the x-axis (horizontal)
Dependent Variable – this variable should be placed on the y-axis (vertical)
Scales – be sure to make your graph large enough to include all data points and use as much of the graph as possible. You can use different multiples (of 5, 10, 20, or more) on your axis.
Legend – short description of the graph’s data.

15. Graph the following information
Use the data in the table below to complete the graph. Remember to title your graph, label your axes properly, set up an appropriate scale, and make a legend for your graph
Depth in Meters
Number of bubbles/min Plant A
Number of Bubbles/min Plant B 2 29 21 5 36 27 10 45 40 16 32 50 25 20 34 30

16. Graph the following information
Diabetes is a disease affecting the insulin producing glands of the pancreas. If there is not enough insulin being produced by the cells, the amount of glucose in the blood will remain high. A blood glucose level above 140 for an extended period of time is not considered normal. This disease, if not brought under control will lead to sever complications and even death.
Use the data in the table below to complete the graph. Remember to title your graph, label your axes properly, set up an appropriate scale, and make a legend for your graph.
Time after eating (hours)
Glucose level in ml/liter of blood in person A
Glucose level in ml/liter of blood in person B
0.5
170
180 1
155
195
1.5
140
230 2
135
245
2.5
235 3
225 4
130
200

17. Results of Experiments
Based on results of experiments and communication with others, The following results of are possible:
Revisit Hypothesis: A hypothesis can be supported, modified, or rejected based on collected data. A hypothesis is a tentative explanation that accounts for a set of facts and that can be tested by further investigation.
Develop a Theory: A theory is an accepted explanation of a large body of information, experimental and inferential, and serves as an overarching framework for numerous concepts. It is subject to change as new evidence becomes available.
Formation of a Law: A law is a statement of fact meant to describe, in concise terms, an action. It is generally accepted to be true and universal.

18. How Theories Develop
A theory is a well tested explanation that unifies a broad range of observations
More than one theory may be needed to explain a circumstance
i.e. why are some marsupial mammals in Australia and others in nearby island?
No theory is absolute truth!
All theories may be revised or replaced by a more useful explanation