How an Experiment is Conducted

1
How an Experiment is Conducted
2
Identifying and Writing a Problem Statement

• The problem is the first step of the scientific
  method. Only one variable at a time should be
  tested so that the results can be easily
  clarified.

3
Examples of testable Problems

1. Which flavor of gum last the longest?
2. Which brand of toilet paper is the strongest?
3. How many pennies can fit in a cup full of water
   without it overflowing?
4. What factor causes mold to grow on bread the
   quickest?
5. Which type of battery will last the longest?

4
Your Turn to Write a Testable Problem

• Create three examples of testable problems.
  Remember that you should only be testing on
  variable at a time.
• __________________________________________________
  ______________
• __________________________________________________
  ______________
• __________________________________________________
  ______________

5
Conducting Research

• Research involves gathering background
  information related to your experiment from
  another source.
• Name some ways or sources you could use to
  gather information for an experiment.
• Ex Scientific Encyclopedia_____________________
• __________________________________________
• __________________________________________
• __________________________________________
• __________________________________________

6
Creating a Hypothesis

• A hypothesis is a prediction or educated guess
  as to what you believe the outcome of your
  experiment will be based on research or general
  knowledge.
• Your hypothesis must always be written as an If
  ., then statement before the experiment is
  conducted.
• If a hypothesis is wrong after the experiment is
  completed, that does not indicate that the
  experiment was a failure. Some great ideas and
  inventions have resulted from incorrect
  hypotheses. Just as much knowledge, if not more
  can be gained form an incorrect hypothesis as
  from a correct one.

7
Examples of Problems and Hypotheses.

• What is the effect of cigarette smoke on
  household plants?
• If I test to see how cigarette smoke affects
  plant, then it will ______________________________
  __________.
• 2. In a natural filtration system, how should
  rocks, sand, and dirt be layered to get the
  cleanest water?
• If I test to see how materials in a natural
  filtration system should be layered, then their
  order from top to bottom will be
  __________________________________________.
• 3. How does exercise affect heart rate?
• If I test to determine how exercise affects the
  heart rate, then it will _________________________
  ___.

8
Practice Writing a Hypothesis

• Write a hypothesis for each of the following
  problems using an If, then statement.
• Example Problem
• Which is a more effective heat source, coal,
  natural gas or electricity?
• Hypothesis
• If coal, natural gas and electricity are tested
  to see which provides the warmest heat in the
  shortest time, then it will be natural gas.

9
Write a hypothesis for each of the following
problems using an If, then statement.

• Which brand of soap gets rid of germs the best?
• Hypothesis
• If _____________, ___________, and ___________
  soap are tested to determine which gets rid of
  germs best then, _________
• will work best.
• 2. Which brand of sneakers will allow you to
  jump the highest?
• Hypothesis
• If __________________________________________
  are tested to determine which will allow you to
  _________________________ then, the
  ___________________ will work _______________?
• 3. How many pounds of weight can be held by a
  bridge made out of 30 popsicle sticks?
• Hypothesis
• _____ weights are placed on a bridge made of
  ________________ then, the bridge will be able to
  hold _______________ before it breaks.

10
Write a Hypothesis for these 2 problems
completely on your own.

• 1. Which soft drink Coke, Sprite or Dr. Pepper
  is the most corrosive?
• Hypothesis
• 2. Will a 40, 60 or 100 watt light bulb last the
  longest?
• Hypothesis

11
Variables

• A variable is a factor that can affect the
  outcome of an experiment.
• There are 3 types of variables
• Constant Variables
• The variable(s) in an experiment that are kept
  the same.
• Examples
• Same amount of sunlight
• Same amount of water
• Same size and type of pot
• Same type of soil

12

• 2. Independent variable
• The experimental variable, or the variable that
  is changed.

This is what you are testing, what you have
control over. You can change or alter this
variable in the experiment.
Example If fertilizer is fed to a tomato plant
then the plant will produce larger tomatoes
because the fertilizer helps the plant grow and
produce bigger fruit. The fertilizer is the
independent variable. You have control over
whether it is added or not. It is the variable
you are experimenting with or that you can
change. It is the independent variable.
13

• Dependent variableThe variable that is effected
  by the independent variable.
• This is the variable that you measure or observe
  during your experiment.

Example If fertilizer is fed to a tomato
plant then the plant will produce larger tomatoes
because the fertilizer helps the plant grow and
produce bigger fruit.
The tomato size is the dependent variable. The
size of the tomatoes is effected by the
fertilizer. Tomato size is the variable you are
measuring and observing during the experiment.
The fertilizer which is the independent variable
may or may not effect the size of the tomatoes.
14
Writing a Materials List

• The materials list should be written in list
  form, with each item numbered. All materials or
  substances, their amounts, and any needed
  equipment must be included.
• Here is an example for an experiment which tests
  to see how many styrofoam peanuts can be dissolve
  in 1/3 cup of acetone.
• Materials List
• 1. 1500 (or more) styrofoam peanuts
• 2. 1 can of acetone (any size)
• 3. 1/3 cup measuring cup
• 4. 1 clear jar

15
Your Turn to Write a Materials List

• Below create a materials list for the ingredient
  and materials needed to make a hot fudge sundae.

16
Materials needed to make a banana split

1. 1 ice cream scoop
2. 1 bowl
3. 1 spoon
4. Measuring spoons
5. 3 scoops of Vanilla ice cream (1/2 cup for each
   scoop)
6. ¼ cup of chocolate syrup
7. ¼ cup ofpineapple ice cream topping
8. ¼ cup of strawberry ice cream topping

• 1 banana (sliced in half)
• ½ cup whip topping
• 3 teasponns of chopped nuts
• 1 cherry

17
Writing the Procedure

• The procedure should be written in list form,
  with each step numbered. This makes it much
  easier to follow.
• Clear, precise, and detailed directions should
  be given in each step.
• It is essential that you give good directions
  that others can easily repeat your experiment
  exactly, without questioning any part of it.

18
Steps for Dissolving Styrofoam Peanuts
Procedure

1. Gather materials.
2. Pour 1/3 cup of acetone into the jar.
3. Begin putting Styrofoam peanuts into the jar one
   at a time, counting out loud as you go.
4. Continue putting peanuts into the jar until they
   no longer dissolve.

19
In the space below, write the procedures for
making a hot fudge sundae.
20
Procedures for making a banana split.

1. Gather materials.
2. Open ice cream and put three scoops in a bowl.
3. Peel the banana and slice it into ¼ inch thick
   slices
4. Put the banana slice around the ice cream scoops.
5. Open the chocolate syrup, and the jars of
   pineapple and strawberry topping.
6. Using the spoon put approximately ¼ cup of
   pineapple topping on one scoop of the ice cream.
7. Repeat step 6 using the chocolate syrup and the
   strawberry topping.
8. Spray approximately ½ cup of whip topping over
   the top of the ice cream.
9. Measure ¼ cup of chopped nuts and sprinkle over
   the whip topping.
10. Place 1 cherry on top of the center scoop of ice
    cream.
11. Put remain ingredients away and enjoy eating your
    banana split.

21
Collecting Data

• Collecting data requires observations. When we
  think about observations, most of us
  automatically think of the sense of sight, since
  that is the sense we most often use to observe
  however, scientific observation may require the
  use of your other senses as well. (smell, touch,
  hearing, taste and sight).
• In science we often record one of two types of
  data.
• Qualitative data or observations which involve
  the use of our sense to record things we see,
  smell, hear, feel or taste.
• Or
• Quantitative data or observations that involve
  numbers or amounts.
• To record our observations we use table and
  graphs.

22
Qualitative vs. Quantitative Observations

• Read each statement carefully. Decide if the
  statement is a qualitative or quantitative
  statement and place an X in the appropriate
  answer box.

Qualitative Quantitative
The kittens fur is soft and fluffy.
The container holds one gallon of gasoline.
The puppy weighs less than seven pounds
The lemonade is yellow and tastes very sour.
The American flag has and 13 red and white stripes and 50 stars.
23
Making Tables Graphs
24
Data Tables

• Data tables are an excellent way to display
  information. After putting information in a table
  you can easily set up a graph to illustrate the
  data.
• Tables have several features in common.
• All tables as well as graphs should have a title
  to let the reader know the subject of the table
  or graph.
• Most tables consist of a series of rows and
  columns. These rows and columns intersect to form
  cells.
• A row is a series of cells going horizontally
  across the table.
• A column is a series of cells going vertically or
  up and down the table.
• You should tell where a particular piece of data
  is by describing the row and column.

25
Examples

• FAVORITE PETS OF STUDENTS

DOGS CATS FISH BIRDS HORSES
12 10 3 2 5
This sort of table lends itself to a bar or
column graph as the information is a one time
response. A circle graph could also be used.
26
Favorite Student Weekend Activity
A bar or column graph would be an excellent
illustration of this data as it is a one time
survey of the student population.
27
Average Daily Temperature for February 1-5 in
Degrees Fahrenheit

• This sort of data table lends itself well to a
  line graph as the temperature is a continuous
  item that fluctuates.

28
Percent of Hours in a Day Spent on Activities

• This sort of table's data would be well
  illustrated by a circle or pie graph as it show
  the parts of a whole - in this case hours of a
  day and how they were spent.

29
Bar Graphs
Bar graphs are an excellent way to show results
that are one time events, especially samplings
such as surveys, inventories, etc.
Favorite Student Weekend Activity
Visit w/Friends
Talk on Phone
Play Sports
Go to the Movies
Play Computer Games
of students 0 2 4 6 8 10 12 14 16 18 20 22
Notice that in this graph each row is labeled.
30
Column Graphs

• Column graphs are similar to bar graphs. Both
  have grid lines going horizontally and
  vertically. The column graph is also used for one
  time or single events rather than continuous
  events.

FAVORITE PETS OF STUDENTS
In the column graph the data is presented in
columns. The category names can be on the graph
or underneath the column. It is not necessary to
assign different colors to the columns although
you could do so and then attach a legend that
would explain the different colors and which
category they stood for.
31
Line Graphs

• A line graph is useful in displaying data that
  changes continuously over time. The example below
  shows the changes in the temperature over a week
  in February.

This line graph shows the degrees of temperature
going up the vertical axis and the days of the
week on the horizontal axis. The points for the
temperature for each day are connected by a
line. Line graphs should show a change over a
period of time or a comparison such as speed.
32
Circle Graph

• A circle graphs is used when the data can be
  expressed as percentages of a whole. The entire
  circle shown in a pie graph is equal to 100 of
  the data. The graph is divided as a baker's pie
  would be into slices that represent the
  proportional amounts of time spent on each
  activity.

To the right of the pie chart is a legend that
tells which color stands for which category. In
addition, the percents are also near the pie
slice that stands for that particular amount of
time spent.
33
Your Turn to Create

• Use the information on the next page to create
  each of the following items
• A data table of letter grades, number of
  students, average number of hours the students
  studied and the percentage of students receiving
  each letter grade (A-F)
• A bar graph of student grades and the number of
  students in the class.
• A line graph showing the students grades and the
  number of hours they studied
• A circle graph showing the percentage of students
  in the class that earned each letter grade.
• Note Dont forget to add a title for each graph
  and to labeled the axis'.

34
Student Grades
5 As 25 10 hours
8 Bs 40 8 hours
3 Cs 15 5 hours
1 D 5 1 hour
3 Fs 15 0 Hours
35
Data Table

1. Create a data table of letter grades, number of
   students, average number of hours the students
   studied and the percentage of students receiving
   each letter grade (A-F)

Grades Number of students Percentage Average of Hours Studied





36
Bar Graph
Create a bar graph of student grades and the
number of students in the class.
8 6 4 2 0
of Grades
A B C D F
Grade
37
Line Graph
Create a line graph showing the students grades
and the number of hours they studied
Students Grades by Average of Hours Studied
A B C D F
G R A D E
0 1 2 3 4 5 6 7 8
9 10 11 12 13 14 15
38
Circle Graph
Create a circle graph showing the percentage of
students in the class that earned each letter
grade.
Percentage of Student Grades Earned
39
Writing a Conclusion

• The conclusion must be written in paragraph form.
• The 1st paragraph should tell if the hypothesis
  was right or wrong. If the hypothesis was wrong
  tell why. Likewise if it was right give data to
  show that is was right.
• The 2nd paragraph should identify the independent
  variable, constant variables and the variables
  that could not be controlled.
• The 3rd paragraph should list at least two
  experimental extensions that could be done in the
  future.
• The 4th paragraph should explain at least two
  concepts learned from the experiment.

40
Sample Experimental/Lab Write-Up

• Problem How many times will the top pop off a
  film canister using water and Alka-Seltzer?
• Research When water and Alka-Seltzer come in
  contact with one another, they undergo a chemical
  reaction in which CO2 gas is released. When this
  gas is contained in a film canister, it will blow
  the top off.
• Hypothesis If water and Alka-Seltzer are
  combined to see how many times the top will blow
  off a film canister, then it will be 6 times.

41

• Materials
• 1. 1 film canister with a tight fitting lid
• 2. 200 ml or water
• 3. 3-5 Alka-Seltzer tablets
• 4. paper towels
• 5. tape
• 6. a partner

42

• Procedure
• Tape 1 Alka-Seltzer under the top of the film
  canister.
• Fill the canister ½ full of water.
• Tightly place the top on the film canister.
• Hold the top and bottom, shake up and down for 10
  seconds
• Release the top.
• Have your partner retrieve the top and put ot
  back on the film canister.
• Repeat steps 4-6 until all the Alka-Seltzer and
  gas is used. (You may refill the canister with
  water at any time.)
• Use the paper towels to dry off the canister
  before taping another Alka-Seltzer to the lid.
• Repeat the experiment at least 3 times record
  the number of pops for each trial.

43

• Data
• Top Pops

Test Conducted Number of Pops
Test one 3 pops
Test two 5 pops
Test three 10 pops
44
Graphs
45
A Sample Conclusion

• The hypothesis was not correct because it said
  the top would pop off 6 times and it did not. It
  popped off 3 times in the first test, 5 times in
  the second test, and 10 times in the third test.
  However the average calculated for the three test
  is 6 times.
• The variable being test was the number of times
  the top would pop off of the canister. He
  constant variables in this experiment were the
  type of canister used, the amount of water added,
  the amount of Alka-Seltzer used, the amount of
  time the canister was shaken. The variables that
  could not be controlled were how high the top
  flew, how far the top flew, how long it took to
  retrieve the top, how much water came out with
  the gas, and if the alka-Seltzer flew out with
  the gas. These variables could not be controlled
  because they all depended on the amount of gas
  building up inside the canister.

46

• A few extensions of this experiment, or examples
  of what could have been done differently, are to
  use baking soda and vinegar instead of water and
  Alka-Seltzer, or to combine all of these
  ingredients at once. Instead of the number of
  pops a test could have been done to see how high
  or how far the top popped off. In addition, more
  Alka-Seltzer and more water could have been used
  with each test.
• One concept gained from this experiment was the
  chemical reaction produced by the water and
  Alka-Seltzer. Another concept learned was that
  the production of bubbles indicates that a gas is
  present. Finally it was noted that this type of
  chemical reaction can be dangerous if the top is
  pointed toward someone when released.

47
A Few Final Notes

• All experiments should be testable not a
  research paper, a survey, demonstration, or
  model.
• A minimum of five different test should be
  performed to get accurate results.
• Some experiments allow you to use controls. Such
  an experiment uses a separate group to compare
  with your test group. For example, if you test to
  see if fertilizer affects plants, then you should
  have a control experiment that is not subject to
  any fertilizer but is otherwise identical to your
  experimental group in every way. If you use a
  control, it should be discussed it in the second
  paragraph of the conclusion.