GRADE 8 SCIENCE
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Bacteria Lab!
This activity will prove to you that your mother was right! “Wash your
hands with soap and water!” A petri dish has been prepared with
nutrient agar (a seaweed derivative with beef nutrients added). It is an
ideal way to reveal the bacteria hiding all around you. You may not
believe what is hiding on you, around you and all over your school!
Hypothesis:
I hypothesize that _______________________________ is the dirtiest
place in the school. I hypothesize that ___________________________
is the cleanest part of the school.
Materials:
Partners (1 for recording, 1 for swabbing)
4 petri dishes per group
4 Sterile cotton swabs
4 paper squares
Procedure:
1) Watch a demonstration of swabbing a surface and a petri dish.
2) Choose your partners. Decide what you would like to swab and let Mrs.
Nickel know and record it on the board, and record it at the bottom of this
page. Write your test areas, group names, and date on the BOTTOM of your
petri dish. ***Lids can be lost, moved and misplaced so it is important to
write your lab information on the bottom of your petri dish!***
3) Take your sterile swabs, paper squares, and petri dishes to your testing
locations.
GRADE 8 SCIENCE
4) Using your paper square, mark your testing section. Discard your used
square.
5) Open a sterile swab package and remove the cotton swab. Rolling your
swab between your fingertips using consistent and firm pressure, swab
your test area 6 times in one direction, turn and swab it 6 more times in the
second direction.
6) Hover the lid of your petri dish over the bottom, and with your cotton
swab, “paint” your swab onto your petri dish. Be sure to roll your cotton
swab while “painting,” then turn your petri dish a 1/3 turn and repeat. Do
this three times in total to ensure the agar gel is covered completely. DO
NOT DAMAGE THE AGAR GEL. Replace the lid of your petri dish.
7) Store your petri dish upside down in the plastic container on Mrs. Nickel’s
desk.
8) DO NOT open petri dishes once we start growing bacteria. We do not know
what kind of bacteria we are growing and to be safe we must keep the petri
dishes closed.
9) Make a prediction at the bottom of this lab as to which bacteria swab will
produce the most bacteria colonies? The least?
10)
Check on your bacteria swabbed petri dishes daily and count the
colonies that are beginning to grow. Record your results below.
11)
At the end of the week, write a statement about your prediction and
what you learned.
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GRADE 8 SCIENCE
14) What kind of cell is a bacterium cell? What organelles do they have?
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15) How do bacterium cells grow?
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16) Draw a bacterium cell.
17) How do they differ from animal and plant cells?
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18) How is a bacterium cell different from a virus?
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GRADE 8 SCIENCE
Date:
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