Dissection - the alternatives
What the alternatives to dissection are depends on the objectives of a particular practical. Objectives could include:
There are so many alternatives to animals in teaching now that they can't all be listed. Find what you need in the
NORINA database
, which is available on the internet. NORINA lists over 3700 alternatives, and this number is increasing all the time. You choose:
The ideas which follow are only a few examples of what can be done.
Apart from models and books, there are several high quality computer
programs that let students explore the inside of a human body, organ by
organ, layer by layer. These programs include:
To find out more about these products you can visit the web site of
Amazon in the UK and search for
Bodyworks Classic. Also search on
Human Body and Medicine for additional titles.
In small groups students research one organ or organ system. Their
task is to construct a labelled 3D model, made of any materials they
think best illustrates the organ's appearance and function. Each group
explains their organ's structure and function, and their choices in its
construction, to the class (1).
Possible teaching aids include models, videos and computer programmes. For example:
This 31 minute video clearly shows all the major organ systems of a rat,
and uses animations to demonstrate how some organs move to carry out their
functions. There are questions to stimulate thought at the end of each
section. There are also exercises to investigate important biological
concepts, such as surface area:volume ratio (2).
This is a computer program containing colour photos and diagrams of
layer after layer of the rat's body. Students decide by a click of the
mouse which organs they want to investigate in detail. Test questions
are included in the programme (3).
There are 2 sites where you can "dissect" a frog. To visit these sites, click on the following:
Adventurous teachers have made their own hyper-card stacks, using the
Apple Computer software application called HyperCard. In one case the
teacher not only made his own programme to teach students frog anatomy,
but also taught them how to make their own hyper-card stacks. They then
chose their own topics to research and present, for example, kidney
function or heart disease. Some of these instructional programmes were
so good, that students were intending to market them! (4)
The most relevant way of studying physical processes is for students to
use themselves as experimental subjects. Ways of doing this range from the
sophisticated (computer interfaces) to the simple (classroom exercises).
This company produces a range of equipment and computer software to measure and record various physical processes:
FlexiComp: reflex arcs
SpiroComp: lung volume
CardioComp: electrocardiography
PhysioGrip: muscle physiology
With each product students investigate some aspect of their own
physiology. For more information about these products, visit the Intelitool
web site.
Effective experiments can also be done more simply and cheaply. They can
be used to investigate topics such as muscle physiology and reflex arcs.
One student from each group flexes and extends the fingers as fast
as possible for 5 consecutive 30 second intervals. After a rest of 30
seconds s/he does the same again. The same sequence is then repeated
with the non-preferred hand. Another student operates the stopwatch,
and a third counts and records the number of flexes/interval. Results
and graphed and analysed (5).
Pairs of students investigate examples of human reflexes. For example,
compare pupil size in normal light and in bright light. Separate the eyes
with a book and shine light into only one eye. Compare the size of the
two pupils. Produce a knee jerk reflex by tapping the patella. To what
extent is the reflex altered by strenuous physical exercise, or intense
mental concentration. Produce a plantar reflex by scratching the sole
of the foot. Can this reflex be altered (6)?
Students in groups seek out references which will help them to explain how
humans walk. What muscle contractions, joint movements and blood supply
are involved? In what ways are humans adapted to walking on 2 legs? As an
exercise in comparative anatomy and physiology, prepare a report on what
anatomical structures are required by various animals that use different
forms of movement (eg flying, swimming, gliding, wriggling, etc) (7).
Some of the previous examples already incorporate this aspect, for
example, the choice of materials in making human organs, the exercise
on surface area:volume ratios in the rat dissection video, and the
structures needed for different forms of movement.
The outdoor investigation of plant and animal adaptation is an excellent
way of relating form and function. A mangrove swamp is a good example,
although other habitats can be used. Through carefully constructed
worksheets, students can be guided to observe the habitat of mangroves
and the structures which help them survive there. Attention can also
be directed to the birds and molluscs which live in mangroves, and the
characteristics which suit them to this environment (8).
Assign groups of students a specific habitat. They are to design an
imaginary creature suited to this habitat. What size and colour would
it be? What skin covering would it have? How would it control its body
temperature? How would it move? What muscles and bone structures would it
need to support this movement? What would it eat, and how are its body
parts suited to this diet? Each part of the creature's anatomy must be
justified in relation to its habitat and be consistent with biological
principles (6).
There are endless ways to encourage careful observation. For example,
the previously mentioned excursion to a mangrove swamp requires detailed
observations. Any local habitat, such as a creek bed, tidal pools or
nature reserve can be used in a similar way.
Birds in the school grounds make a good subject to study (binoculars would be useful). For example:
Groups of students design a bird feeder to be set up in a particular part
of the school. A talk by a bird care organisation may be useful to get
ideas. The feeder is regularly observed and observations are recorded
in a journal. Students also design and carry out a research project
with their feeder. Findings are communicated to the class via a poster
presentation. For a detailed plan of this project on the internet visit
Backyard Birding .
The key to developing manual skill is practice, which is why one, or
even a few dissections are not enough to improve skill (10). Preparing
microscope slides is a good way to practise, for example, preparing leaf
sections to investigate the cell arrangement. Students can prepare many
slides, they can get immediate feedback by looking at the slide under
the microscope, and they can practise until they are satisfied with
their work.
Students first observe the whole flower and draw the sepals, petals,
stamens and carpels. Then they examine the structure and position of
the stamens. How is this flower likely to be pollinated (birds, bees,
butterflies, wind?). How does the flower structure encourage pollination?
Next students remove an anther and observe the structure of pollen under
a microscope. Why would a plant produce so much pollen? Students then
carefully bisect the ovary to expose the ovules, which also are examined
under the microscope. How does a pollen grain which lands on the stigma
reach the ovules? (6)
Respect depends on recognising the value and worth of others. Wildlife
films can do a great deal to show how remarkable animals are, how they
have their own unique characteristics, but also share many characteristics
with us. Some of the projects already mentioned can also encourage
respect, for example, excursions where you leave the environment as you
found it, and the bird feeding observations. Interactions with animals
in natural environments can be useful, for example, open range zoos,
good wildlife sanctuaries, fauna rescue centres, or any environment
suited to the needs of animals. One thing is certain: interaction with
dead animals in dissections does not encourage respect.
A story written by a year 11 student in Melbourne illustrates the lack of respect for animals in dissections. go to
Voices for the animals
and read "Death of the Innocent".
If you want to know more about why dissection is wrong and unnecessary for learning, go to
Dissection - the Arguments
.
NORINA will select all the products in its database that match this description.
Human anatomy
BodyWorks Classic
ADAM Essentials
Student Research Project:
Animal anatomy
Investigation of a Mammal (Rat)
The Rat Stack
Frog Dissections on the Internet
University of Virginia School of Education
Lawrence Berkeley National Laboratory
Student Research Project
Study physical processes
Intelitool products
Aerobic vs anaerobic respiration
Reflexes
Student Research Project
Relate form and function
Investigate adaptation
Student Research Project
Develop observation skills and understanding of scientific methods
Student Research Project
Student Research Project
Develop manual skill
Flower dissection
Encourage respect for animals and nature
References