Classifying macroinvertebrates (Years 7 and 8)
Lesson plan
Introduction
Macroinvertebrates (waterbugs) are a key
indicator of waterway health. This series of
lessons focuses on scientific classification of
organisms.
Students classify macroinvertebrates by their
observable structural features and highlight the
biodiversity that can be found in freshwater
environments. Students develop dichotomous
key using their own criteria for classifying
macroinvertebrates and consider how biologists
use keys in their field work.
Activity 1: Identifying macroinvertebrates
Victorian Curriculum F–101 links:
Levels 7 and 8
Science
Science Understanding
Science as a Human Endeavour
Science and technology contribute to finding
solutions to a range of contemporary issues;
these solutions may impact on other areas of
society and involve ethical considerations
Biological sciences
There are differences within and between
groups of organisms; classification helps
organise this diversity
Students identify macroinvertebrates in a water
sample and consider how these organisms can be used to indicate the ecological health of a
waterway.
Activity 2: Classifying macroinvertebrates
Students explore how organisms are classified and devise a dichotomous key for
macroinvertebrates.
1
Victorian Curriculum and Assessment Authority (VCAA)
<http://victoriancurriculum.vcaa.vic.edu.au/> Accessed 14 August 2016.
Activity 1: Identifying macroinvertebrates
Students identify macroinvertebrates in a water sample and consider how these organisms
can be used to indicate the ecological health of a waterway.
Equipment
Waterbug collection equipment—net, pole, bucket and gloves
Images of the waterway sampling site
One bucket of water with a macroinvertebrate sample from local waterway
For each group:
One copy of the A3 laminated Macroinvertebrates ID chart (attached) and/or
access to an online guide such as A beginner’s guide to waterbug identification
or a hardcopy version from
<http://www.waterwatchmelbourne.org.au/content/volunteer_monitoring/monitoring_
water_bugs_(macroinvertebrates)/monitoring_water_bugs_(macroinvertebrates).asp
>
One copy of the Macroinvertebrate data form (download from
<http://www.waterwatchmelbourne.org.au/content/library/Macroinvertebrate_Data_Fo
rm.pdf>
Waterbug sorting and viewing equipment—one white catering tray for sorting, an ice
cube tray, five spoons, magnifying glasses
Digital microscope and interactive whiteboard or data projector, if possible
Preparation
Collect macroinvertebrate sample from a healthy section of a waterway. Take a photo to
show students where the sample came from. After the lesson, make sure that you take them
back to the same place you collected them. Ensure that all safety requirements are followed.
Activity steps
1. Ask students to list animals that live in a waterway. Once students have done so, pinch
your thumbs and forefingers together to make a small diamond. Explain to students the
animals we will be looking at are on average the size of the space between your fingers.
2. Explain that these animals support the food chain, and without them the turtles, platypus,
fish, birds and frogs wouldn’t be able to survive.
3. Introduce the term ‘aquatic macroinvertebrates’ or waterbugs. Explain that this term
refers to the fact that these animals live in water and have no backbone.
4. Tell students that you visited a local waterway and sampled it for macroinvertebrates.
Show students the image of the waterway you sampled. Explain where and how you
collected the sample. In your description, explain the terms riparian vegetation; verge;
riffle; aquatic plants; slow-flowing, deep pools; muddy, sandy or rocky bottom. A drawing,
diagram or enlarged, laminated photographs may be useful.
5. Display the Scope Waterbugs video [3:13] found on the Melbourne Water website at
<http://www.melbournewater.com.au/getinvolved/protecttheenvironment/Pages/Waterbu
g-Census.aspx>
6. Show students the water samples and explain that they will be looking at the
macroinvertebrates. Explain how to look for macroinvertebrates in the sample and how
to identify them using the Macroinvertebrate ID charts or the A beginner’s guide to
waterbug identification. Use this opportunity to demonstrate how to care for the live
organisms ethically i.e. using spoons for carefully lifting the macroinvertebrates from the
sample, disturbing them as little as possible.
7. Demonstrate how to use equipment correctly. For example:

using the spoon to carefully lift the macroinvertebrates from the sample into the ice
cube trays for observation

using magnifying glasses to look for features on our macroinvertebrates

using the identification charts (with photos) to help identify common
macroinvertebrates

not stirring up the sample—it makes it harder to see the macroinvertebrates!
8. Organise students into small groups. Explain that they will be looking for
macroinvertebrates in a tray. Assign the groups a tray to look at.
9. Using the naked eye or magnifying glasses, students will make some observations of the
sample of macroinvertebrates such as:

the number of different types

the numbers of each type

the size, shape, colour of the macroinvertebrates

features such as legs, tail, wings or mouth parts.
If possible, use a digital microscope to display macroinvertebrates using a magnification
of 10X.
Students draw a labelled diagram of each macroinvertebrate in their notebooks showing
the shape and any distinguishing features such as legs, tail, wings, shells or mouth parts
etc. These drawings can be used in Activity 2.
10. Explain how to complete the Macroinvertebrate data form.
11. Add macroinvertebrate sample to catering trays with five or so students at each tray.
Provide each group with a macroinvertebrate data form to complete. Remind students of
time limits during activity. Assist students as necessary with identification.
12. Collate the macroinvertebrate data forms on the class data sheet (or whiteboard).
Discuss sensitivity of macroinvertebrates that were found and what they indicate about
the water quality of the local waterway. What factors would affect the health of the
waterway?
13. Explain that in the next lesson we will explore how biologists classify macroinvertebrates
into groups.
14. Ask students what kind of actions can they take to help protect their waterways?
Examples:

Increased nutrients affect water quality. Therefore you need to pick up dog poo when
walking your dog as it enters waterways via stormwater.

Make sure litter goes in the bin as litter can enter waterways via stormwater.

If you like to see a range of animals around your local waterway, do your bit to limit
water pollution.

Look after the small macro-invertebrates and you are looking after the larger animals.

Plant trees to increase shade and oxygen levels.
Key messages
Our waterways support a diverse range of plant and animal life, including native fish,
frogs and platypuses. They are worth looking after.
Everyone can help improve local rivers and creeks by reducing stormwater pollution –
simple things like picking up after your dog, binning rubbish and fixing oil leaks in your
car can reduce the impacts.
15. Collect macroinvertebrate samples so they can be returned to place they were collected.
Activity 2: Classifying macroinvertebrates
Students use macroinvertebrates to explore how biologist use classification levels to identify
species.
Equipment
Interactive whiteboard or data projector, if possible
For each group:
One copy of the A3 laminated Macroinvertebrates ID chart (attached) and/or
access to an online guide such as A beginner’s guide to waterbug identification
or a hardcopy version from
<http://www.waterwatchmelbourne.org.au/content/volunteer_monitoring/monitoring_
water_bugs_(macroinvertebrates)/monitoring_water_bugs_(macroinvertebrates).asp
>
One set of Macroinvertebrate cards (Attached)
One sheet of paper
Activity steps
1. Explain that biologists need to be able identify each type of organism and to do this
they group all living things on Earth into the following categories.
Kingdom
Phylum
Sub-phylum
Class
Order
Family
Genus
Species
2. Taxonomy is the science of classifying animals. Display the following table of the
major taxonomic levels.
3.
7.
Level
Kingdom
4.
5.
6.
8.
Classification of Humans
Animalia
Phylum
Chordata
Sub-phylum
Vertebrata
Class
Mammalia
Order
Primates
Family
Hominidae
Genus
Homo
Species
sapiens
3. Explain to students vertebrates (animals with backbones) include birds, amphibians,
mammals, fish and reptiles. All others are considered invertebrates.
4. Explain to the students how we can use a key to identify the macroinvertebrates.
Dichotomous means divided in two parts or classifications. With a dichotomous key,
there are at least two options to choose from.
5. Display the Virtual sampling learning object at
<http://lrrpublic.cli.det.nsw.edu.au/lrrSecure/Sites/LRRView/7396/applets/virtual_dip/virtu
al_sampling.html> to show how macroinvertebrates can be identified with a dichotomous
key.
6. Working in groups, students choose drawings of four or five different macroinvertebrates
they observed in Activity 1 to devise a dichotomous key to identify these
macroinvertebrates. Alternatively, distribute copies of the Macroinvertebrate cards to
each group. Students select the criteria that can distinguish each of the organisms they
are working with.
7. Model how students might use the criteria such as:

legs/no legs

tail prongs/no tail prongs

gills for breathing/no gills for breathing.
8. On a sheet of paper, students create a flow chart of their classification with each branch
of the flow chart separating the macroinvertebrates with a question. Questions should
focus on features: for example ‘Does it have six legs?’ rather than ‘Is it an insect?’
Students continue with their questions to separate the macro-invertebrates.
9. Groups share their classification flow charts with the class. Students combine their ideas
to produce a final flow chart. Discuss why field biologists commonly use dichotomous
keys to identify organisms rather than an identification chart or guide.
Teacher background
These classification levels were devised by Carolus Linnaeus (1707–1778), a Swedish
botanist, zoologist and physician.
The classification levels become more specific towards the bottom, more general towards
the top.
Many organisms belong to the same kingdom but fewer belong to the same phylum and so
on as you go down the taxonomic levels.
Two animals that belong to the same family and genus are more closely related than two
animals that only belong to the same family.
You can learn a lot from the scientific name, e.g. Homo sapiens:
Homo = self or same, meaning same as me = humans
sapiens = wise
Therefore, Homo sapiens means wise human.
Macroinvertebrate cards