Competency 1 Review
Scientific Method and Graphing
Important Safety Symbols
 Biohazard: organisms
and other biological
materials may be
harmful to humans
 Radiation: radioactive
material nearby
Important Safety Symbols
 Potentially harmful
fumes
 Sharp object
Important Safety Rules
 Never smell anything
directly from a test
tube. Point test tube
away face and gently
waft gas toward
nose.
Important Safety Rules
 Wash your hands and
clean up your lab
station after the
experiment.
 When in doubt, just
TELL THE TEACHER!
 Broken glassware or
equipment
 Spills
 Injury
 Contact with chemical
on skin or in eyes
Lab Equipment
Graduated Cylinder
 Used to measure precise
volumes of a liquid.
 To correctly measure
volume, look at the bottom
of the curved line called the
meniscus.
 Make sure you are reading it
at eye level!
 How many mL are in this
graduated cylinder?
 Answer: 44
Lab Equipment
Triple Beam Balance
 Measures the mass of
objects
Lab Equipment
Triple Beam Balance
 How to read:
What is the total mass of
of this object?
500 + 40 + 5.2 = 545.2
Lab Equipment
Beaker
Flask
 Both can be used for stirring, mixing, measuring and
heating liquids
Lab Equipment
Pipette
 Used for transferring liquids
and/or measuring small
amounts of liquids
(a few mL).
Bunsen burner
 Used for heating.
Microscopes
 To move image to the left, move stage to the right. To
move image to the right, move stage to the left.
OPPOSITE!
 Your microscope has 3 magnifications: Low, Medium,
and High. Each objective will have written the
magnification. In addition to this, the ocular lens
(eyepiece) has a magnification. The total magnification
is the ocular x objective
Low
Medium
High
Magnification
Ocular Lens
Total
Magnification
4x
10x
40x
10x
10x
10x
40x
100x
400x
Scientific Method
Listing the Steps
1.
Make an Observation
2.
Define the Problem
3.
Research the Problem
Ask Question
Do Background
Research
Construct
Hypothesis
4.
State the Hypothesis
5.
Experiment to test Hypothesis
6.
Collect and Record Data
7.
Analyze Data
8.
Make a Conclusion
9.
Determine Limitations
10. Report Results
Think!
Try Again
Test with an
Experiment
Analyze Results
Draw Conclusion
Hypothesis is True
Hypothesis is False
or Partially True
Report Results
Scientific Method
Creating a Hypothesis
 A hypothesis is:
 An educated guess, trial answer, possible
solution, prediction
 Must be a statement
(usually in “If…then” format)
 Must be testable or measurable
 Is based on your research and previous
experience
Scientific Method
Creating a Hypothesis
Step 1: Define the problem.
 Example: Does the temperature of water
affect the amount of sugar that will dissolve in
it?
Step 2: Make a prediction, a.k.a. hypothesis.
 If the temperature of water is increased, then
the amount of sugar that can be dissolved in it
will increase.
A hypothesis must be testable!
 You must make a prediction that is
measurable by an experiment.
 If you are not predicting a measurable
outcome, there is no way to test the
hypothesis.
How do you test a hypothesis?
Experimenting
 Use a Controlled Experiment
 An experiment that tests only one factor at a time by
using a comparison of a control group and an
experimental group.
 Control Group
 The group that the scientist changes nothing in. The
Control group is used for comparison.
 Experimental Group
 The group that the scientist has changed something. It
is the variable in the experiment where you want to see
how this condition affects something.
Graphing in Science
 Graphs help us visualize numerical data.
 There are 3 different types of graphs:
 Bar graphs
 Pie graphs
 Line graphs
Bar Graph
 A bar graph is used to show
relationships between groups.
 The two items being compared do not
need to affect each other.
 It's a fast way to show big differences.
Notice how easy it is to read a bar
graph.
Chocolate Milk Sold
120
100
Amount Sold
• Question:
On what day was
the most chocolate
milk sold?
• Answer:
Wednesday
112
80
76
72
60
53
40
33
20
0
Monday
Monday
Wednesday
Friday
Tuesday
Tuesday
Thursday
Wednesday
Day
Thursday
Friday
Circle Graph or Pie Graph
 A circle graph is used to
show how a part of
something relates to the
whole.
 This kind of graph is
needed to show
percentages effectively.
 Question: Which day
was the least
chocolate milk sold?
 Answer: Thursday
Chocolate Milk Sold
Monday
Tuesday
Wednesday
Thursday
Friday
Line Graph
 A line graph is used to show
change over time.
 It's clear to see how things are
going by the rises and falls
a line graph shows.
Chocolate MIlk Sold
120
Amount Sold
100
80
60
40
20
0
Monday
Tuesday
Wednesday
Day
Chocolate
Thursday
Friday
Line Graph
 Question: On which day was there a drop in milk sales?
 Answer: Thursday
Chocolate MIlk Sold
120
Amount Sold
100
80
60
40
20
0
Monday
Tuesday
Wednesday
Day
Chocolate
Thursday
Friday
Graphing Experimental Results
 Identify the Variables
 Number and label each axis
 Plot the points
 Draw the graph
 Give your graph a title
Graphing Experimental Results:
Identify the Variables
Setting up an Experiment:
Control Group
 Example:
Six bean plants are to be tested to see what happens if light is
taken away. The all have the same type of container, the same
amount of soil, and they will receive the same amount of water.
Three will be placed in a sunlit window and 3 will be placed in a
dark closet for 2 weeks.
 What is the control group?
 The plants in the sunlit window
 Why? Plants are naturally found in areas with at least some
sunlight. Nothing was changed about their normal habitat
regarding sunlight.
Setting up an Experiment:
Control Group
 Example:
Six bean plants are to be tested to see what happens if light is
taken away. The all have the same type of container, the same
amount of soil, and they will receive the same amount of water.
Three will be placed in a sunlit window and 3 will be placed in a
dark closet for 2 weeks.
 What is the experimental group?
 The plants in the dark closet.
 Why? Photosynthetic plants are not normally found in
completely dark environments. The scientist wants to see how
this change will affect this group of plants.
Setting up an Experiment:
What is a variable?
 A variable is something that can be changed.
 In an experiment it is a factor that is different from one
group to another.
 Controlled variables– (constants) All the variables that
remain constant
 Independent variable– (manipulated variable) factor that
is purposely changed
 Dependent variable– (responding variable) factor that is
measured; factor that may change because of independent
variable; what scientist wants to observe
Independent Variable
 Example:
Six bean plants are to be tested to see what happens if light is
taken away. The all have the same type of container, the same
amount of soil, and they will receive the same amount of water.
Three will be placed in a sunlit window and 3 will be placed in a
dark closet for 2 weeks.
 What is the independent variable?
 Light—the scientist purposely changes the amount of light
available to the plants.
Dependent Variable
 Example:
Six bean plants are to be tested to see what happens if light is
taken away. The all have the same type of container, the same
amount of soil, and they will receive the same amount of water.
Three will be placed in a sunlit window and 3 will be placed in a
dark closet for 2 weeks.
 What is the dependent variable?
 Plant growth—the scientist will observe and measure how
much the plants grow as a result of the light and dark
conditions
Controlled Variables (Constants)
 Example:
Six bean plants are to be tested to see what happens if light is
taken away. The all have the same type of container, the same
amount of soil, and they will receive the same amount of water.
Three will be placed in a sunlit window and 3 will be placed in a
dark closet for 2 weeks.
 What are the constants?
 Same container, amount of soil, amount of water
 In a controlled experiment, you must keep everything the
same except one variable!
Experiments must be VALID
 Results of an experiment are not reliable if the
experiment is not conducted properly.
 When conducting an experiment, always
make sure to:
 Complete at least 3 trials
 Only change one variable at a time
 Have a control group to compare with
experimental group
What is wrong with this experiment?
James wondered if music had an effect on plant
growth. He set up an experiment where 25 bean plants
were placed in a chamber where music was played and
25 bean plants were placed in an identical chamber
where music was not played. He placed one chamber
outside in the summer heat and one chamber he kept
inside his house. He gave all plants the same amount of
fertilizer, soil, and water. At the end of two weeks plant
height was measured.
What is wrong with this experiment?
James wondered if music had an effect on plant
growth. He set up an experiment where 25 bean plants
were placed in a chamber where music was played and
25 bean plants were placed in an identical chamber
where music was not played. He placed one chamber
outside in the summer heat and one chamber he kept
inside his house. He gave all plants the same amount of
fertilizer, soil, and water. At the end of two weeks plant
height was measured.
Identify the Variables
A study was done to see if leaves added to soil had an effect on
tomato production. Tomato plants were grown in four large tubs.
Each tub had the same kind and amount of soil. One tub had 15 kg
of rotted leaves mixed in the soil and the second had 10 kg. A third
tub had 5 kg and the fourth had no leaves added. Each tub was
kept in the sun and watered the same amount. The number of
kilograms of tomatoes produced in each tub was recorded.





What is the control group? Tub with no added leaves.
What is the experimental group? All tubs with added leaves.
Independent variable: Different kg of leaves added to each tub
Dependent variable: Kg of tomatoes produced
Control variables: Same size tub, same type and amount of soil,
same amount of sunlight and water
Identify the Variables
Bart believes that mice exposed to microwaves will become extra
strong. He decides to perform this experiment by placing 10 mice
in a microwave for 10 seconds. He compared these 10 mice to
another 10 mice that had not been exposed. His test consisted of a
heavy block of wood that blocked the mouse food. He found that
8 out of 10 of the microwaved mice were able to push the block
away. 7 out of 10 of the non-microwaved mice were able to do the
same. He recorded how many mice could push the block away.





What is the control group? 10 non-microwaved mice
What is the experimental group? 10 microwaved mice
Independent variable: microwave
Dependent variable: Number of mice that can push the block
Control variables: Number of mice kept same between
groups, same block of wood