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My favourite experiments - connecting teachers and ideas
Article · June 2022
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1www.scienceinschool.org/article/2022/my-favourite-experiments
Science is universal, but how we teach it varies greatly from
one place to another. All teachers have at least one favourite
experiment that they particularly love to share, and new
ideas are always being created, evolved, and shared by amazing
teachers around Europe and beyond. However, some ideas
can be slow to cross barriers, whether they be geographic, cultural,
linguistic, or curricular. With ‘My Favourite Experiments’,
Michael Gregory has made it his goal to facilitate the spread
All teachers have at least one favourite experiment that they are eager to share.
Read on to learn more about monthly experiment sharing sessions and discover
some low-cost physics experiments to try out in your own classroom.
ISSUE 58 – June 2022 Topics Engineering | General science | Physics | Resources
of good ideas between teachers. Since 2017, he has cycled
through over 30 countries (including all 25 mainland EU states)
asking educators the question “What’s your FAVOURITE EXPERIMENT?”
and sharing their answers on his YouTube channel.
He also runs monthly online experiment sharing meetings
for teachers, and some physics examples from a recent
session are featured in this article.
My favourite experiments –
connecting teachers and ideas	
Michael Gregory, Gordana Varnica, and Panagiotis (Takis) Lazos
The online experiment sharing sessions
The online ‘experiment shares’ are monthly meetings online for teachers to share their
­favourite experiments.[1]
Experiments have been shared by teachers from Canada, Greece,
Italy, Romania, Serbia, Germany, Ireland, UK, Brasil, USA, France, Portugal, Bulgaria, Albania,
and Croatia, and the list continues to grow!
Most months feature eight to ten experiments from around the world, and cover topics ranging
from primary school science to advanced physics topics, with most being appropriate for
a wide range of ages, usually upper primary to lower secondary (approx. 10-16 years old).
The goal is for teachers to share experiments with each other, so everyone is encouraged to
prepare a short demo of one of their current favourite experiments. Teachers who are not yet ready to share experiments
of their own are also very welcome to come along to watch, but active participation is encouraged.
For more information, including dates of upcoming events, please see https://www.scienceonstage.fr/experiment-share/.
Image courtesy of Michael Gregory
2www.scienceinschool.org/article/2022/my-favourite-experiments
Issue 58 – June 2022
To give you a taste of what to expect in these monthly experiment
sharing sessions, we’re sharing a small sample of
highlights from a recent meeting in this article. Using simple
and inexpensive materials, these experiments can show
some surprising phenomena. The entry barrier should be
low enough that you can try them out immediately in your
own classroom, either as a quick demo to pique the interest
of younger students or in greater detail to teach more advanced
physics topics. This selection features physics experiments;
however, the monthly meetings also include biology,
chemistry, geology, and general science.
Activity 1: Pythagoras’ cup – Panagiotis
(Takis) Lazos, Athens, Greece
A Pythagoras’ cup, also known as a Tantalus cup or a greedy
cup, is a cup that contains a syphon, which will automatically
drain the contents of the cup if it is filled beyond a certain
point. This is a fun demonstration of pressure in communicating
vessels (tube and cup) and the syphon principle.[2]
It can be constructed in roughly 20–30 minutes, and demonstrated
in less than 5 minutes.
Watch the recording
Curricular connections:
	⦁ primary – inquiry/observation (questioning “why does the
cup empty”, “what do you see”, “what do you infer”, etc.)
	⦁ middle/secondary school – pressure, syphon principle,
engineering, and construction (students can make,
­evaluate, and improve their own designs)
The Pythagoras’ cup demonstrating the syphon principle
Image courtesy of Panagiotis (Takis) Lazos
Materials
	⦁ A transparent plastic cup or bottle
	⦁ A length of flexible plastic tube (around 25 cm)
	⦁ Hot glue
Procedure
1.	 Pierce a hole in or near the bottom of the cup.
2.	 Glue one end of the plastic tube, so it can drain through
the hole, and seal the connection with glue as necessary,
so the cup doesn’t leak.
3.	 Bend the tube such that the other end is inside the cup
near the bottom. The top of the bend should be lower
than the top of the cup, and the height of the bend will
determine the maximum fill level.
4.	 The cup should hold water (without leaking) when filled
to a height lower than the bend in the tubing, but, when
this level is exceeded, the water in the tube will create a
syphon, which will drain the entire contents of the cup.
Discussion
Pythagoras’ cups made of clay and other materials are often
sold as souvenirs in Greece, Cyprus, and the Eastern Mediterranean.
Made from opaque materials, it is impossible to
see inside, and it is often difficult for students to understand
the relatively simple principles at play. By making their own
transparent versions in the lab, they can gain a more intuitive
understanding of pressure in fluids.
Activity 2: The simplest motor in the
world – Gordana Varnica, Požega, Serbia
This simple homopolar motor is a fun and easy demonstration
of the Lorentz force – a current-carrying wire in a magnetic
field will experience a force perpendicular to both the flow
of current and the magnetic field.[3]
This can be set up in minutes,
or can be used for longer discussions on electromotive
force, with students being asked to consider the direction of
the magnetic field and current to predict the direction of force.
Watch the recording of the meeting and a video of the ex-
periment.
Curricular connections:
	⦁ primary/middle school – creating a simple circuit and the
conversion of electrical to kinetic energy
	⦁ secondary school – electromagnetic induction, Lenz law,
and an introduction to electric motors and dynamos
A battery and a copper wire are used to demonstrate
the Lorentz force.
Image courtesy of Gordana Varnica
3www.scienceinschool.org/article/2022/my-favourite-experiments
Issue 58 – June 2022
Materials
	⦁ Neodymium battery – round/coin size or smaller
	⦁ Battery (AA, AAA, or similar)
	⦁ Copper wire
Procedure
1.	 Stand the battery on the magnet
2.	 Bend the wire so that it can sit with one end on the top
of the battery and the other end completing a circuit
through the magnet to the bottom of the battery.
3.	 The wire should experience an electromotive force due
to the electric current flowing through a magnetic field.
With some care, it should be possible to bend/place the
wire in such a way that it will spin around the battery
continuously.
Discussion
Simple homopolar motors like this were one of the first demonstrations
of electromagnetism two centuries ago, and they still
manage to fascinate generations of young scientists today!
Activity 3: Beer-bottle thermometer –
Michael Gregory, Paris, France
Make a simple gas thermometer from an empty glass bottle
and a handful of simple materials.[4]
Quick and easy to make,
this can be done in a single 45-minute lesson in primary
school to demonstrate a simple thermometer, or for a more
advanced lesson in secondary school (approx. 14–18 years
old), the thermometer can be calibrated and results extrapolated
for an experimental calculation of absolute zero.
Watch the recording
A thermometer built from a straw and a bottle
Image courtesy of Michael Gregory
Curricular connections:
	⦁ primary – difference between temperature and heat,
types of thermometers, and measuring temperature
	⦁ middle school – expansion of gases/thermal expansion
in general, measurement theory, and calibration
	⦁ secondary school – gas laws/thermodynamics, taking
measurements and evaluating uncertainty and sources
of error, extrapolating data graphically and algebraically,
and experimental calculation of absolute zero
Materials
	⦁ Empty glass bottle (beer, wine, juice, etc.)
	⦁ One-hole stopper of suitable diameter to fit the bottle
	⦁ Balloon
	⦁ Thin-diameter transparent tubing
	⦁ Water (may be coloured for better visibility)
For calibration
	⦁ Lab thermometer
	⦁ Warm/cold water
Procedure
1.	 Insert tubing into the stopper, allowing 1–2 cm of extra
length below the bottom of the stopper.
2.	 Insert the balloon into the top of the bottle and carefully
fill with water (the balloon should not completely cover
the opening before it is full, or else the pressure of air
inside the bottle will prevent the balloon from filling).
3.	 Once the balloon is full, insert the stopper into the bottle.
Normally, once a seal has been formed, the stopper
will displace its own volume of water up the tube, and
so, your starting temperature should have a few centimetres
of water visible above your stopper.
4.	 The thermometer should now be ready to use to demonstrate
changes in temperature.
5.	 Calibration – the thermometer can be calibrated by placing
it in two water baths of different known temperatures.
Within reasonable uncertainty, the thermometer
can be considered to operate at constant pressure, and
therefore, an increase in volume is proportional to an
increase in temperature, and a linear scale can be used
to both interpolate and extrapolate between the known
temperatures.
Discussion
This simple gas thermometer can be used for a rough experimental
measure of absolute zero, by extrapolating the
calibration until the volume of gas in the bottle is zero. To
do so, the height of water in the tube should be converted
into volume, so we can extrapolate to find the temperature
4www.scienceinschool.org/article/2022/my-favourite-experiments
Issue 58 – June 2022
at which the volume of the gas in the bottle should be zero.
This can be done graphically or algebraically, depending on
the learning outcomes of this calculation.
For more details on calibration and troubleshooting, please
see this document.
Summary
Awesome teachers around Europe are doing excellent experiments
every day, and reflective practitioners learn from
their experience, always improving, tweaking, and coming up
with new experiments. My Favourite Experiments is a collection
of projects to gather and share some of the best experiments
across Europe and around the world, and these
monthly experiment sharing meetings are a way of keeping
up with some of the best ideas, as they are continually being
improved by great teachers like yourself.
This is a small sample of the nearly 100 experiments that
have been shared by tens of teachers during the first year
of these monthly meetings. Many of the best educators in
Europe look forward to getting together each month to share
their newest favourite experiments. I hope you’ll join us next
month to share in the fun!
References
[1] Experiment share welcome page:
https://tinyurl.com/ExperimentShare
[2] 6 November 2021 experiment share recording:
https://youtu.be/MvXm83_E6YA?t=1983
[3] 20 December 2021 experiment share recording: ­
https://youtu.be/OOEdxqagN48?t=198
[4] Beer-bottle thermometer instructions:
https://tinyurl.com/MFE-Thermometer
Resources
	⦁ Watch full recordings and written descriptions of past
online experiment shares.
	⦁ Browse the experiments shared during the my favourite
experiment cycle tour.
	⦁ Students who are interested in sharing experiments may
be interested in the twin project Young Enthusiastic Scientists
(YES!) International.
	⦁ Find free virtual science camps, including Particle Physics
for Kids.
	⦁ View and take part in an annual homemade science video
festival for students and teachers.
	⦁ Run physics experiments with objects you can find in
your house: de Winter J (2022) Physics with everyday
objects: springy sweets, a universe in your pocket, and
drawing circuits. Science in School 56.
Michael Gregory is a Scientix Ambassador and member
of the Science on Stage Team France. When not busy
teaching in Paris or connecting with teachers and students
online, he also loves to travel, including volunteer
teaching in Ghana, Cambodia, and Peru.
In 2022, he hopes to once again cycle across Europe to
gather new experiments. For more information, including
his tentative route and how to ask him to make a
detour to your school, please see:
https://www.scienceonstage.fr/michael-gregory.
Gordana Varnica is a physics teacher at the Sveti Sava’
Požega high school in Serbia. She’s been promoting
science festivals in Serbia for more than 20 years. She
is also one of the founders of Gimfest, a science and art
festival at the school. Her main goal is to make physics
exciting and accessible for students of all abilities.
Panagiotis (Takis) Lazos is a physics teacher in Greek
secondary education, head of the fourth Laboratory
Center of Natural Sciences of Athens, and a PhD student
in the Faculty of Primary Education of the National and
Kapodistrian University of Athens. He likes to try new
versions of classical science experiments and to use
smart mobile devices and microcontrollers in the school
science laboratory.
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