Skills of Inquiry & Communication
Wet Lab
Sampling Pond Organisms
Purpose: to apply scientific investigation skills to observe, draw, and classify pond
organisms. To appreciate the diversity of organisms in pond water.
SBI3U Curriculum Expectations:
A1.1 formulate relevant scientific questions about observed relationships, ideas,
problems, or issues, make informed predictions, and/or formulate educated hypotheses
to focus inquiries or research
A1.2 select appropriate instruments (e.g., sampling instruments, a microscope, a
stethoscope, dissection instruments) and materials (e.g., dichotomous keys, computer
simulations, plant cuttings), and identify appropriate methods, techniques, and
procedures, for each inquiry
A1.4 apply knowledge and understanding of safe laboratory practices and procedures
when planning investigations by correctly interpreting Workplace Hazardous Materials
Information System (WHMIS) symbols; by using appropriate techniques for handling
and storing laboratory equipment and materials and disposing of laboratory and
biological materials (e.g., preserved specimens); and by using appropriate personal
protection
A1.5 conduct inquiries, controlling relevant variables, adapting or extending procedures
as required, and using appropriate materials and equipment safely, accurately, and
effectively, to collect observations data
A1.6 compile accurate data from laboratory and other sources, and organize and record
the data, using appropriate formats, including tables, flow charts, graphs, and/or
diagrams
A1.8 synthesize, analyse, interpret, and evaluate qualitative and/or quantitative data to
determine whether the evidence supports or refutes the initial prediction or hypothesis
and whether it is consistent with scientific theory; identify sources of bias and/or error;
and suggest improvements to the inquiry to reduce the likelihood of error
B2.2 classify, and draw biological diagrams of, representative organisms from each of
the kingdoms according to their unifying and distinguishing anatomical and physiological
characteristics (e.g., vertebrate or invertebrate organisms, vascular or nonvascular
plants)
B2.3 use proper sampling techniques to collect various organisms from a marsh, pond,
field, or other ecosystem, and classify the organisms according to the principles of
taxonomy
Sources:
Dunlop, J., et al. (2010). Biology 11. Whitby: McGraw-Hill Ryerson Limited.
TEACHER NOTES
Prior Knowledge:
• Students should have a base understanding of how to use and care for a light
microscope.
✦ Carry the microscope with one hand under the base and one hand holding the
arm
✦ Do not touch the lens with your fingers; use only lens tissue to clean the lens
surface
✦ Focus first using the coarse adjustment knob, with the low-power objective lens
in position
• Students should understand how to draw biological diagrams properly.
✦ Usually, a blank sheet of paper is used for each specimen, however an
observation sheet is used in this lab to compile all data, including a drawing
✦ Pencil should be used for the title, drawing, and all labels
✦ Labels should be placed at the right of the drawing
✦ Students should draw what they see, even if it is different from text book
drawings; all organisms are unique
✦ Shading is not usually necessary; draw with simple, clean lines
• Students should know how to calculate drawing magnification.
✦ Measure the diameter of the field of view (FOV) using a clear ruler
✦ When looking at the specimen, estimate the number of times the specimen could
fit across the field of view
✦ Determine actual length of specimen:
Actual Length = diameter of FOV / # specimens across FOV
✦ After drawing your sketch, measure the length (or the same measurement as
done on the specimen) of the drawing, using the same units!
✦ Calculate the drawing magnification:
D.M. = drawing length / actual length = ______ x
• An understanding of taxonomic ranks and distinguishing characteristics of organisms
from different kingdoms is necessary.
Context:
• This lab would probably be executed mid-way through the Diversity of Living Things
unit, because of the prior knowledge required.
Suggestions:
• Be sure to check the quality of slides before the lab. Prepare the slides by covering
the names of species if they are written on the slides (duct tape is preferred).
• If students are unsure of microscope and biological drawing procedures, provide a
handout or chalkboard instructions so that they have something to refer to throughout
the lab.
• Ideally, there should be two students per microscope for optimal viewing opportunities.
• This lab uses prepared slides of phytoplankton, so students can be given a variety of
slides to represent their sample of pond water. Alternatively, samples of pond water
can be ordered from a laboratory or collected from a natural source so that students
have the opportunity to prepare their own slides and consider sampling error, relative
abundances of species, and other factors while conducting the lab. If using live
samples, additional materials will be needed: thread (for slowing the movement of
organisms in the medium), methyl cellulose solution (to slow down movement of any
protozoans), iodine (to stain organisms for better viewing), paper towel (to draw stain
across slide), methylene blue stain (to further stain plankton; this will kill specimens),
dropper, depression slide, cover slip. In addition, safety precautions should be noted:
do not eat or drink while performing the lab; be cautious that iodine and methylene
blue may stain clothing and skin; wash hands with soap and water upon completion of
the lab; remind students to turn off the microscope when not viewing organisms, as
the heat from the light will harm live specimens.
Limitations
• Students can benefit from collecting their own samples of pond water. The
procedures for collecting and considerations for scientifically rigorous methods can be
discussed. However, if implemented, this activity would require several hours of
preparation, and likely a field trip day.
STUDENT WORKSHEET
Sampling Pond Organisms
The microscopic organisms that float at or near the surface of bodies of water are
collectively known as plankton. Phytoplankton are plankton that carry out
photosynthesis. They may be members of the kingdom Bacteria, Protista, or Plantae.
Zooplankton move and consume other organisms. They may be members of the
kingdom Protista or Animalia. In this investigation, you will use techniques of sampling
and classification to measure the diversity of organisms in pond plankton.
Pre-lab Questions
1. What distinguishing features will you look for to help you identify different types of
plankton?
2. Describe how you can collect live samples of pond plankton. What methods would
ensure that your samples accurately reflect the diversity of the pond ecosystem?
Materials
• prepared slides of phytoplankton
• light microscope
• microscope ruler
• illustrated guide of pond micro-organisms
Procedure
1. Select one slide at a time to observe. Look at it under your microscope, starting with
low power, then medium power, and then high power if necessary.
2. Using the illustrated guide, identify the specimen. In your table, record the kingdom
and genus. Sketch the specimen and indicate the magnification. NOTE: some
specimens in the organism key are stained differently than your prepared slides.
3. Return to low power and repeat the procedure with another species. Observe as
many different species as you can.
Analyze and Interpret
1. How did you distinguish between protists and the members of other kingdoms?
2. Which kingdom showed the most diversity in your sample?
Conclude and Communicate
1. Name three factors that might increase the diversity of plankton species living in a
pond. Name three factors that might decrease the diversity of plankton species in a
pond.
2. If you were to collect live samples of pond plankton, would you expect to find more
species of phytoplankton or zooplankton? Suggest why.
Extend further
1. How would the diversity in a local pond ecosystem be affected if run-off from lawns in
a local subdivision was allowed to flow directly into the pond? Research the impact of
phosphates and other pollutants on a pond ecosystem.
STUDENT WORKSHEET - ANSWER KEY
Sampling Pond Organisms
The microscopic organisms that float at or near the surface of bodies of water are
collectively known as plankton. Phytoplankton are plankton that carry out
photosynthesis. They may be members of the kingdom Bacteria, Protista, or Plantae.
Zooplankton move and consume other organisms. They may be members of the
kingdom Protista or Animalia. In this investigation, you will use techniques of sampling
and classification to measure the diversity of organisms in pond plankton.
Pre-lab Questions
1. What distinguishing features will you look for to help you identify different types of
plankton?
Shape of organism, method/physiology for locomotion, method of
obtaining nutrition (in live specimens).
2. Describe how you can collect live samples of pond plankton. What methods would
ensure that your samples accurately reflect the diversity of the pond ecosystem?
Samples should be collected from various locations in the pond, and at
various depths.
Materials
• prepared slides of phytoplankton
• light microscope
• microscope ruler
• illustrated guide of pond micro-organisms
Procedure
1. Select one slide at a time to observe. Look at it under your microscope, starting with
low power, then medium power, and then high power if necessary.
2. Using the illustrated guide, identify the specimen. In your table, record the kingdom
and genus. Sketch the specimen and indicate the magnification. NOTE: some
specimens in the organism key are stained differently than your prepared slides.
3. Return to low power and repeat the procedure with another species. Observe as
many different species as you can.
Analyze and Interpret
1. How did you distinguish between protists and the members of other kingdoms?
Protists are mostly unicellular, whereas plants and animals are mostly
multicellular.
2. Which kingdom showed the most diversity in your sample?
The protists; they can be fungus-like, plant-like, or animal-like.
Conclude and Communicate
1. Name three factors that might increase the diversity of plankton species living in a
pond. Name three factors that might decrease the diversity of plankton species in a
pond.
Examples include: diversity of plant-life, varying depths within the pond,
diversity of animal-life.
Examples include: decreased diversity of plant- and/or animal-life,
consistent pond depth/temperature/sunlight levels.
2. If you were to collect live samples of pond plankton, would you expect to find more
species of phytoplankton or zooplankton? Suggest why.
Answers will vary, as this is an open-ended question.
Extend further
1. How would the diversity in a local pond ecosystem be affected if run-off from lawns in
a local subdivision was allowed to flow directly into the pond? Research the impact of
phosphates and other pollutants on a pond ecosystem.
Run-off might contain harmful chemicals and pollutants, which might kill
organisms in the pond ecosystem, thus altering the interconnected web of
organisms in the ecosystem.