Name: _____________________________
Class: _____________________________
Date: _____________________________
Epidemic!
Bio Outcome 5: Recognize and design a valid experiment – B) Hypothesis
Bio Outcome 6: Design an experiment that uses appropriate controls and variables.
Bacteria Growth Lab
It Came From The Boys’ Bathroom!
(or, How I Learned to Grow and Love Bacteria)
Introduction: Our goal during this lab is to see where bacteria are growing all around us
here in school. This lab will take at least one week. We will first sample different places
in the school for microscopic life – particularly bacteria, and then give them good
conditions for growing. Every day we will observe and record the progress of the
bacterial growth. At the conclusion of this lab we will report on the number, size, and
exponential growth of bacteria.
As a group:
What are some of the places you will go to find bacteria? Work on the table alone for
3 minutes. Then, when your teacher tells you, circle the places you and your group
members agree on!
CLEAN
DIRTY
(I don’t think there are any bacteria here.)
(This place is crawling with bacteria!)
Hypothesis:
You must decide where to find bacteria in the school. What is your hypothesis?
 lots of
 sink
My hypothesis: I think we will find _______________ bacteria on the ______________
 no
 doorknob
 some
 toilet seat
 bathroom

 keyboard
 classroom
__________
 table
 gym
in the __________________.
 __________
 _____________
Now write it out on your own:
________________________________________________________________________
________________________________________________________________________
As a group, you must now rank four locations you thought of from dirtiest to cleanest.
These are the locations you will collect bacteria from to compare.
____________________ >
dirtiest
____________________ > ____________________ > ____________________
very dirty
somewhat dirty
least dirty
Materials:
1) Fill in the names of materials using the NOUNS from the box at right:
Nouns:
Lid
Agar
Petri Dish
Swab
Preparing to describe the process:
2) Translate the following VERBS into your language:
RUB in my language is _____________________________.
UNCOVER in my language is _____________________________.
COVER in my language is _____________________________.
PUT in my language is _____________________________.
3) What are some of the conditions on the Petri dish and where we are putting it that
will help the bacteria grow?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Describing Bacteria
Word
Part of
Speech
In My Language
Meaning
Colony
Culture
Edges (also called margin)
Words to describe the colony:
Slimy
Grainy
Smooth
Dry
Rough
Wet
Name:
Measuring Your Bacteria:
Class:
Yesterday we put the bacteria in the incubator and they have been busy
growing and reproducing. Let’s draw, measure, and describe what the Petri dishes
look like. We will describe and measure the growth of colonies on your plate – how
many different kinds and how much bacteria within them.
Today’s Date: _____________________ # of days bacteria have been growing: _______
Location: _______________________________
Drawing:
Qualitative:
How many different types of bacteria colonies do you see? _____________________
Qualitatively describe at least 2 types:
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Quantitative: How much bacteria is on your plate?
Total bacteria area:
. How many squares have a colony in them?
________________
x
# of squares w/ bacteria
x
________________ = _______ mm2
Square area (36 mm2)
Sampled colonies – 2 biggest and 2 smallest. Mark them (#1, #2, #3, #4 on the drawing above)
Colony #
Diameter (mm)
_______________________________________________________________________
The Next Day:
We’ve been away all weekend, and the bacteria have been busily growing. Let’s draw,
measure, and describe what the Petri dishes look like. You must follow the growth of at
least three colonies on your plate – that means you must measure its size everyday.
Today’s Date: _____________________ # of days bacteria have been growing: _______
Location: _______________________________
Quantitative observations:
Drawing:
Colony #
Diameter (mm)
Qualitative observations:
__________________________________
__________________________________
__________________________________
Location: _______________________________
Quantitative observations:
Drawing:
Colony #
Diameter (mm)
Qualitative observations:
__________________________________
__________________________________
__________________________________
Location: _______________________________
Quantitative observations:
Drawing:
Colony #
Diameter (mm)
Qualitative observations:
__________________________________
__________________________________
__________________________________
Today’s Date: ____________________ # of days bacteria have been growing: _______
Location: _______________________________
Quantitative observations:
Drawing:
Colony #
Diameter (mm)
Qualitative observations:
__________________________________
__________________________________
__________________________________
Location: _______________________________
Quantitative observations:
Drawing:
Colony #
Diameter (mm)
Qualitative observations:
__________________________________
__________________________________
__________________________________
Location: _______________________________
Quantitative observations:
Drawing:
Colony #
Diameter (mm)
Qualitative observations:
__________________________________
__________________________________
__________________________________
Today’s Date: ____________________ # of days bacteria have been growing: _______
Location: _______________________________
Quantitative observations:
Drawing:
Colony #
Diameter (mm)
Qualitative observations:
__________________________________
__________________________________
__________________________________
Location: _______________________________
Quantitative observations:
Drawing:
Colony #
Diameter (mm)
Qualitative observations:
__________________________________
__________________________________
__________________________________
Location: _______________________________
Quantitative observations:
Drawing:
Colony #
Diameter (mm)
Qualitative observations:
__________________________________
__________________________________
__________________________________
Today’s Date: _____________________ # of days bacteria have been growing: _______
Location: _______________________________
Quantitative observations:
Drawing:
Colony #
Diameter (mm)
Qualitative observations:
__________________________________
__________________________________
__________________________________
Location: _______________________________
Quantitative observations:
Drawing:
Colony #
Diameter (mm)
Qualitative observations:
__________________________________
__________________________________
__________________________________
Location: _______________________________
Quantitative observations:
Drawing:
Colony #
Diameter (mm)
Qualitative observations:
__________________________________
__________________________________
__________________________________
Name:_______________________Class: ___________________
Date: __________
Bacteria Growth Lab Results
Now that we have followed bacteria growth for almost a week, lets put our data together. For
the three colonies you observed, complete the following tables.
Location Sampled: ___________________________________, Colony # ________
Day
(for example,
Day 2)
Diameter
(mm)
Draw the colony
(Actual Size)
Qualitative Observations
Location Sampled: ___________________________________, Colony # ________
Day
(for example,
Day 2)
Diameter
(mm)
Draw the colony
(Actual Size)
Qualitative Observations
Location Sampled: ___________________________________, Colony # ________
Day
(for example,
Day 2)
Diameter
(mm)
Draw the colony
(Actual Size)
Qualitative Observations
Observation Summary:
In this space, write several words or sentences about how the bacterial colonies looked or
changed over time. Some other things you can talk about are:
 Which location had the most/least bacteria?
 What was a specific observation that was surprising or unexpected?
 Similarities or differences between locations.
 How were the results affected by a problem with this experiment or its controls?
Graphical Representation:
Graph your results on a piece of graph paper. You must include:




Labeled axes
Correct scales on each axis
Legend explaining what each line is.
A different color for each colony.
Making the Graph
Title:
Size of bacteria colonies from three locations in Flushing International High School
Title in my language:
Size of
colony
(mm)
Legend:
Draw the color you used for each line, and write what it is for:
Questions for review and understanding:
(answer in complete sentences, blah, blah, blah)
1) Take a look at your original hypothesis. Rewrite your hypothesis here:
____________________________________________________________________________
____________________________________________________________________________
Was your hypothesis supported? Explain why or why not.
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
2) Describe what happened to your bacteria colonies during the week we observed them by
finishing the sentence below. Write more if you need to!
The number of bacteria increased / decreased (circle one). I know
this because…
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
4) Look at the different results on your group’s Petri dishes. What were some of the
similarities and differences between the bacteria you collected at the different locations?
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
3) How do bacteria increase so rapidly (hint – how do living things make more living things)?
5) Why did Jordan leave one Petri dish unopened?
Extra credit:
Create an informational poster for your classmates. Present the results from this experiment
(pictures, drawings, and descriptions) so we can put it up where you found your bacteria. The
poster should have:
 Location where you found the bacteria
 What the colony looked like after 1 week
 Things people can do to avoid contact or infection from these bacteria.
Name:_______________________Class: ___________________
Date: __________
Bacteria Growth Lab Write-Up
Put the following word into your vocabulary dictionary:
Word
Part of
In my language
Meaning
Speech
Publish verb
to make your writing public. Write and then release
it to a wider audience.
At the end of any experiment, scientists need to publish their results. Published work lets
others see and benefit from the results of the experiment. Just follow the format below:
1st paragraph: Explain why you are doing the experiment (Problem) and what you predict will
happen (Hypothesis)
2nd paragraph: Explain what steps you did (Methods)
3rd paragraph: What did you find out (Observations or Results). (This is a good place to
mention pictures
4th paragraph: What your results mean (Conclusion). You should mention whether your
hypothesis is correct and your reason for saying so. This is also where scientists reflect:



How will these results help people?
What are new questions they have because of this experiment?
What would they do differently if they had to do the experiment again?
Math component:
Imagine humans reproduced like bacteria.
a) How many brothers, sisters, and children would you have in just a week?
b) What would be some of the problems with this?