Physical Toys and Hands on Experiments

Ucke, Christian; Schlichting, H. Joachim: Cylindrical and spherical tops
Physik in unserer Zeit 40/1 (2009) 52 - 54

Simple tops may be produced by the means of the most ordinary ressources, i.e. plastic cones, wooden balls, magnetic balls, etc. While even these simple toys perform the most unexpected movements, more sophisticated models give rise to optical phenomena as well.

Ucke, Christian; Schlichting, H. Joachim: Swinging dolls and skyscrapers
Physik in unserer Zeit 39/3 (2008) 139 - 143

Only physicists and engineers with their affinity for playful thinking will recognize the connection of dolls and the underlying physical principles of a tuned mass damper. This technique is of tremendous importance and is used to protect the structural integrity of skyscrapers in the course of earthquakes or strong winds.

Ucke, Christian; Schlichting, H. Joachim: 3-dimensional portraits in glass
Physik in unserer Zeit 39/1 (2008) 34 - 35

Powerful lasers engrave three-dimensional images of objects in glass. By this means one may create realistic portraits. Apart from being fascinated their aesthetic appeal their common observer may ask the question by which means it has been possible to copy the portray into a solid block of glass. And, what is even more astonishing, when observed from from the opposite direction, the portrait looks like a hollow mask.

Schlichting, H. Joachim; Suhr, Wilfried: Kinetic colors
Physik in unserer Zeit 38/4 (2007) 198-200

Someone who moves his hand from left to right before his eyes while straddling his fingers will observe a magnificent color-phenomenon. But where do the colors come from if there is no colored light-source present?

Schlichting, H. Joachim
A rainbow without rain
Physik in unserer Zeit 37/5 (2006) 242 - 244

While a beautiful natural rainbow cannot be observed very often, a similarly colored bow may be produced anytime by the means of a plexiglass tub full of water an a common overhead projector. Strictly speaking, however, this is no real rain-bow. His spectral blaze of color and the ease of its creation are nonetheless fascinating.

Schlichting, H. Joachim: Of the magic of the Hui-machine
Physik in unserer Zeit 37/1, 31-33 (2006)

The Hui-machine, a toy which is continuously rediscovered and renamed, fascinates by its almost magic behavior. Its "magic" may yet be explained by simple physical principles.

Schlichting, H. Joachim: Attractive balls
Physik in unserer Zeit, 36/5, 243 (2005).

Almost everybody knows the Click-Clack-Machine, which is also called Newtons-Cradle. When one of the balls hits the string of balls, it will stand still after the collusion, while the last ball at the end of the string continues the motion at the same velocity at which the first one hit the string. This is a common demonstration of the conservation of impulse and energy. There is however a version of this machine which appears to break this rule.

Ucke, Christian; Schlichting, H. Joachim: The spinning paper-clip
Physik in unserer Zeit 36/1, 33-35 (2005).

Paper-clips are ubiquitious. They are yet not only useful to restore order to stacks of paper, they may also be used in amazing physical experiments. In these contexts they may serve as simple spins or illustrate the form of chains and hanging bridges.

Schlichting, H. Joachim: Paradoxical springs from the perspective of the second law of thermodynamics
MNU 57/2, 78-80 (2004).

Situations which exhibit stark contrasts to our common expectations oftentimes offer valuable physical insights. This may also be the case if they have hitherto been labeled as paradox and thusly been commonly neglected in educational literature. Notwithstanding, these phenomena are of particular didactic value, because they put physical and everyday concepts to the test and encourage physical argumentations.

Schlichting, H. Joachim; Ucke, Christian: The world's simplest electric motor
Physik in unserer Zeit 35/6, 272-273 (2004).

The word's probably simplest electric motor consists of nothing but a cylindrical magnet, a screw, a common 1.5V AA battery and a short wire. Its construction and working principles are presented in this paper.

Schlichting, H. Joachim; Ucke, Christian (English translation by Jonathan Williams): A fast, high-tech, low cost electric motor construction
This article is a modified version which was published originally in German in the journal: Physik in unserer Zeit 35/6, 272-273 (2004).

Schlichting, H. Joachim; Ucke, Christian: Un motor eléctrico de construcción sencilla, bajos costes y alta tecnología
Este artículo es una versión modificada del original publicado en alemán en la revista: Physik in unserer Zeit 35/6, 272-273 (2004).

Schlichting, H. Joachim; Ucke, Christian: Thermodynamic disenchantment
Physik in unserer Zeit 33/6, 284-286 (2002). Every year in the days before Christmas people set up their freshly dusted christmas-pyramids. Apart from its metaphorical meaning the candlelit rotation of the latter may stimulate some very concrete physically motivated thoughts, as well.

Schlichting, H. Joachim; Ucke, Christian: Fascinating Dynabee
Physik in unserer Zeit 33/5, 230-231 (2002).

An appropriately gyrated small spin can accelerates a spherical plastic container to surprisingly high rotation speeds. Originally invented to train the muscles of the wrist, this fitness device may serve as a valuable tool in physics education, as well.

Schlichting, H. Joachim; Ucke, Christian: The Chinese mirror of magic
Physik in unserer Zeit 33/3, 138-140 (2002).

Despite its common appearance the Chinese mirror of magic is no ordinary mirror. What is astonishing about its projection is that it contains the very same ornaments as the relief engraved at its back. Despite being made of massive metal this mysterious mirror thusly appears to be translucent.

Ucke, Christian; Schlichting, H. Joachim: Animal springs
Physik in unserer Zeit 32/1, 44-46 (2001).

The acceleration of a flea in the moment of his jump is more than a hundred times the acceleration of gravity. Although one cannot achieve similar values by attaching springs to small plastic animals, these constructions may well serve as models in a detailed analysis of the remarkable kinetics of these lousy insects.

Schlichting, H. Joachim; Nordmeier, Volkhard: Window crosses painted with light
Physik in unserer Zeit 31/3, 129-130 (2000).

Everybody will have seen reflexions of the sunlight on windows. In most cases the sun renders more or less true images of the pavement or the houses on the other side of the street. The appearance of oval or square spots of light is yet a relatively rare phenomenon, the underlying physics of which shall be explained in this paper.

Schlichting, H. Joachim; Nordmeier, V.: Problems of non-linear physics and non-equilibrial thermodynamics exemplified by the means of hands-on experiments
Physik in der Schule 38/6, 420-424 (2000).

Most students fail to recognize the relevance of non-linear physics and non-equilibrial thermodynamics in their everyday lives. All the more, related phenomena must find their way into physics education. In this context simple hands-on experiments provide ideal means to raise the students' awareness of the presence and influence of such phenomena on their daily lives.

Schlichting, H. Joachim: Hands-on, Low-cost, freehand – experiments between everyday life and physics education
Physik in der Schule 38/4, 255- 259 (2000).

Hands-on experiments are generally simple, they are surprising, motivate viewers to try and copy them and they often have the appeal of magic tricks. Next to their improvised character, their universal availability and their generally low costs, their most important advantage on experiments conducted with using physical comes from the fact that the underlying physical aspects must initially be investigated. Hands-on experiments are therefore especially useful to develop physical ideas and to emphasize qualitative aspects.

Schlichting, H. Joachim: For more than playing with fire... matches in the service of physics education
Physik in der Schule 38/5, 330-334 (2000).

As small ubiquitously available everyday objects, matches inspire to toy around and experiment. Thusly, it appears straight forward to engage them in the service of physics education. Due to their applicability in a broad range of amazing, puzzling and sophisticated contexts, respective experiments often provide ideal points of departure for the development of physical models and processes of concept formation.

Schlichting, H. Joachim: From a single match to an inspiring idea – Hands-on experiments with matches and their boxes
Naturwissenschaften im Unterricht - Physik 57, 26-28 (2000).

From the magnitude of examples of unusual uses of matches and their boxes a selection of physically interesting experiments is presented. The intention is to present a representative overview of the diversity of such experiments.

Behrendt, Helga; Schlichting, H. Joachim: Experiments with simple equipment – between physics and everyday life
Naturwissenschaften im Unterricht - Physik 57, 4-6 (2000).

The influence of technology and the findings of natural sciences on our everyday lives are ubiquitous. Nevertheless, a diminishing interest of students for technical and physical topics is observable. The underlying reasons of this development, as well as the positive effects an extended use of hands-on and other experiments with basic resources may have are presented in this paper.

Schlichting, H. Joachim: Hands-on nature – Natural optical phenomena in hands-on experiments
Praxis der Naturwissenschaften - Physik 48/7, 12-17 + 4. Umschlagseite (1999).

The use of hands-on experiments to introduce natural phenomena in physics classrooms is discussed. Their importance in view of the students ability to transfer and apply basic theoretical concepts in real-world contexts is explained and useful examples are provided.

Ucke, Christian; Schlichting, H. Joachim: Why does champagne bubble?
Physics & Technology Quest 2 (1998).

We come across this phenomenon in everyday life, not only with champagne but also with beer, mineral water and other drinks containing carbon dioxide (CO2). Pearl-like strings of bubbles move upwards in a glass filled with liquid containing CO2. But why does the liquid release the gas dissolved in it? And why does it do this in such a striking way?

Schlichting, H. Joachim; Ucke, Christian: The potion from the Tantalus Cup
Physik in unserer Zeit 29/4, 174-176 (1998).

Sometimes fluids may flow uphill and cause unpleasant surprises for some people and much fun for others. It is demonstrated that this phenomenon is nothing unusual; that, in fact, everybody experiences it every day.

Schlichting, H. Joachim: Magic in physical hands-on experiments
Unterricht Physik 9/43, 16-18 (1998).

Many of the magic tricks which can be found in historical "natural books of magic" are nothing but practical jokes. From the perspective of a modern day physicists, however, some of them may well be regarded as cleverly presented classical hands-on experiments. If the writing of these books had been continued until today, they would probably feature many of the modern hands-on experiments which will are presented and explained in this paper.

Schlichting, H. Joachim: Enchanting, disenchanting, re-enchanting
Unterricht Physik 9/43, 4-6 (1998).

It is possible to make use of the motivational effect of magic in the physics classroom by disguising physical phenomena as magic tricks and demanding students to debunk them by physical means. In these lessons students learn to disenchant mysterious situations by the means of physical concepts. This will improve the students'  ability to view things from a physical perspective and consequently enable them to recognize and understand ostensibly magical phenomena in their everyday-lives. Thusly physics education may well facilitate a re-enchantment the learners' everyday lives.

Schlichting, H. Joachim; Jungmann, Dietmar: Glittering stickers
Physik in unserer Zeit 28/3,112-113 (1997).

The contribution of diffraction to the coloring our everyday lives ranges from the glittering stickers attached to the packages of certain chocolate bars to the colorful reflections on compact discs. Respective phenomena are presented and explained in this paper.

Schlichting, H. Joachim; Ucke, Christian: The energy of music – Rotating Christmas balls
Physik in unserer Zeit 27/6, 262-263 (1996).

In the weeks before December, 24th Christmas songs are playing everywhere. This raises the question whether it were possible to use the acoustic energy of these tunes to power a simple mechanical device like a Christmas pyramid, for example. This would not only save candles, but it would also reduce the probability of fires during the Christmas season. This presents a functional realization of this unusual idea.

Ucke, Christian; Schlichting, H. Joachim: Paradox sand-glasses
Physik in unserer Zeit 27/4, 180-182 (1996).

Although sand-glasses appear to have existed from the beginning of time, it is still possible to devise original constructions. In one design the sand flows from bottom to top – the course of time yet stays the same. In another design the sand-glass literally forgets something – only to remember it later.

Schlichting, H. Joachim; Nordmeier, Volkhard; Jungmann, Dietmar: The big ones always end up at the top – Unmixing by mixing
Physik in der Schule 34/5, 191-193 (1996).

Breakfast cereals and similar blends often appear to be inadequately mixed. The larger ingredients, hazelnuts for example, gather in the upper part of the box, although they have been properly mixed before packaging. The paper proposes a model to physically describe the process of self-organization which is triggered by mixing processes.

Schlichting, H. Joachim: Hands-on experiments. Problems and possibilities of minimal experiments
Physik in der Schule 34/4, 141-146 (1996).

The acceptance of the effectiveness of hands-on experiments in physics education is surprisingly low - especially among teachers at German grammar schools. This article argues in favor of the minimal experiments and explains means by which their didactic value can be maximized.

Ucke, Christian; Schlichting, H. Joachim:
The anamorphic candleholder
Physik in unserer Zeit 27/1,6-8 (1996).

A candleholder fashioned by the famous Danish designer Georg Jensen has several amazing optic qualities. Moreover, the reflections on the physical qualities of this piece of art, which are presented in this paper, constitute a good example of how differently designer and physicist may perceive the very same object.

Ucke, Christian; Schlichting, H. Joachim: Levitron, the hovering top
Physik in unserer Zeit 26/5, 217 (1995).

In everyday language the word levitation is often associated with spiritualistic phenomena. It is also part of the saint myths. Common believe tells us that this effect would suspend gravity. According to a Christian (!) tradition even the metallic sarcophagus of Prophet Mohammed pended freely between two giant magnets. Physicists, however, have a more rational interpretation of such phenomena. 

Ucke, Christian; Schlichting, H. Joachim: The coffee-ballpen or the love-thermometer
Physik in unserer Zeit 26/4, 192-193 (1995).

"Coffee-ballpen", "temper-thermometer" or "love-thermometer": these are only three of the names for a relatively simple toy with interesting physical qualities.

Schlichting, H. Joachim; Ucke, Christian: The glasses are sounding
Physik in unserer Zeit 26/3, 138-139 (1995).

"Every bell has its clepper", at least according to a German proverb. A wine glass, however, produces a similar sound if one rubs its rim with a wet finger. This article provides a physical explanation for this commonly known, yet seldom fully understood everyday phenomenon.

Schlichting, H. Joachim: The teakettle's melody
Physik in der Schule 33/1, 22-23 (1995).

What are the reasons one believes to hear a melody upon listening to the sounds of a teakettle with boiling water in it? What happens in the course of the boiling process? In which ways do variables such as the amount of water in the kettle influence the melody?

Ucke, Christian; Schlichting, H. Joachim: Wobbler, staggerer or two-disk-scooter
Physik in unserer Zeit 25/3, 127 (1994).

Apart from balls and cylinders, there are other rolling objects which maintain a constant distance between their center of mass and the basement throughout the motion. Although they are of no immediate use, they inspire replication and various mathematical, physical and aesthetic reflections.

Schlichting, H. Joachim: Emptiness – Nothing but air. Of the perception of air as a physical system
Praxis der Naturwissenschaften - Physik 43/4, 18 (1994).

One of the most important functions of physics education is to show pupils familiar objects from an unfamiliar perspective: The obvious must become questionable. The perception of air as a physical system may well be considered the most elementary example of the constitutive opposition of the physical perspective and viable perception.

Schlichting, H. Joachim: A physicist's notes on a floating candle
Praxis der Naturwissenschaften - Physik 43/4, 15 (1994).

As ordinary as it may seem at first sight, upon close observation a floating candle will raise questions. Why does the candle float? How long will it remain in its current position? What will happen when it burns down? The physics classroom may answer all these questions and thus improve its students understanding of fundamental physical concepts.

Schlichting, H. Joachim: The candle-pump
Praxis der Naturwissenschaften - Physik 43/4, 12 (1994).

Although the candle-pump is a common hands-on experiment in physics classrooms, its unexpected result and its simple presentation are still fascinating.

Schlichting, H. Joachim: The rescue of a flame
Praxis der Naturwissenschaften - Physik 43/4, 10 (1994).

Only a physicists knows how to save the flame of a candle, which is burning in a bottle with a very narrow neck, from extinction: by the insertion of a divider.

Schlichting, H. Joachim; Ucke, Christian: The flight of the alate seed
Physik in unserer Zeit 25/2, 79 (1994).

Several plant seeds are built in ways which enable them to fly and thusly to spread their species. While most of them are simply carried away by the wind, the aesthetic dive of the seeds of the maple exhibits a multitude of physically intriguing aspects.

Schlichting, H. Joachim: Energetics of the "jumping" hare
Physik in der Schule 32/2, 55 (1994).

It is argued that the analysis of the working-principles of simple toys facilitates a highly motivating approach to the fundamental aspects of the energetics and dynamics of jumping.

Ucke, Christian; Schlichting, H. Joachim: The Galileo thermometer - Termometro lento
Physik in unserer Zeit 24/1, 44 (1994).

Over 300 years in existence and yet still working: This paper celebrates an aesthetically appealing historical thermometer, which is based on basic physical concepts.

Schlichting, H. Joachim; Ucke, Christian:
Why does sparkling wine sparkle?
Physik in unserer Zeit 24/5, 231 (1993).

In a glass with sparkling wine, gas bubbles rise like glittering pearls. But why do they develop predominantly at certain spots, and what determines their way to the surface? These and other questions are addressed in this paper.

Schlichting, H. Joachim: The arrested fall – A physical disenchantment
Physik in der Schule 31/10, 342 (1993).

If we attach a weight to one end of a string that runs across a stick and then let go of the other end, common sense tells us that the weight will sweep the string along on its way to the ground – yet, this is not the case. Magic or physical exigency?

Schlichting, H. Joachim: Why does the disk "buzz"? Physical aspects of an interesting toy
Physik in der Schule 31/5, 179, (1993).

The fiddlestick as it has been described by Jearl Walker in "The Flying Circus of Physics" is a very simple toy, in the eyes of the physicist, however, it is an ideal object for the discussion of various mechanical concepts – especially if a few modifications applied.

Schlichting, H. Joachim; Walter, Reinhold; Waßmann, Harald: With headwind against the wind
Physik in der Schule 31/4, 134 (1993).

The question is, whether there is such a device, which uses energy deprived from the wind in order to move against the latter. Or, in other words: Is it possible that a wind powered vessel moves against the wind?

Ucke, Christian; Schlichting, H. Joachim: The Goethe Barometer
Physik in unserer Zeit 24/2, 91 (1993).

Despite the fact that this simple tool for measuring the pressure of air has not been invented by Goethe, it is quite certain that the famous poet, who was also a meticulous natural scientist, knew the underlying physical principles of this elementary meteorological device.

Schlichting, H. Joachim:
The "mountaineering" cork
Praxis der Naturwissenschaften - Physik 41/3, 45 (1992).

A cork floating on the water surface always moves towards the seam of the vessel. An analogy to the movement of a ball on the concave glass of a clock facilitates a physical explanation of this unusual behavior.

Schlichting, H. Joachim: Playing with the elements: Water and air in hands-on experiments
Praxis der Naturwissenschaften - Physik 41/2, 27 (1992).

Playing does not necessarily require toys. It is also possible to play intensively and oftentimes more creatively with articles of daily use. Several of these less common "games" or - from a physical perspective – hands-on experiments are introduced. What all of them have in common is that they are related to water and air.

Schlichting, H. Joachim: The drinking stork – An evaporation engine
Praxis der Naturwissenschaften - Physik 41/2, 22 (1992).

Does the drinking stork have a hidden source of energy? This question can only be answered by identifying (at least) one of the underlying autonomous processes, which manifest in the kinetic energy of the bird and its dissipative counterpart.

Schlichting, H. Joachim: Top phenomena
Praxis der Naturwissenschaft- Physik 41/2, 11 (1992).

The most important phenomena related to the top and its characteristic motion are described and the underlying physical principles are discussed.  Educationally relevant aspects are outlined and a list of related papers is compiled.

Schlichting, H. Joachim: All kinds of friction – Hands-on experiments with magnetic tops
Praxis der Naturwissenschaften- Physik 41/2, 9 (1992).

A selection of hands-on experiments is proposed and the complex physical interactions of magnetic tops with their surrounding and with each other are analyzed.

Schlichting, H. Joachim: Patience or physics – A basic toy with physical aspects
Praxis der Naturwissenschaften - Physik 41/2, 5 (1992).

The term "dissipative structures", by the means of which Prigogine wanted to emphasize the important role of dissipation in the context of non-equilibrial structures, originally referred to complex many-body problems. In spite of that, even a simple toy may well be regarded as a "dissipative structure".

Schlichting, H. Joachim: Toys in the physics classroom
Praxis der Naturwissenschaften- Physik 41/2, 2 (1992).

The role of real toys and articles of daily use which can be used as toys is discussed in the context of hands-on experiments in the physics classroom. Concrete examples for the didactic value of their playful appeal are provided.

Schlichting, H. Joachim: From up and down to to and fro – Parametric excitement in an hands-on experiment
Naturwissenschaften im Unterricht- Physik 39/10, 22 (1991).

This article discusses the fundamental mechanic principles behind a simple, yet amazing "trick": Although it does seem illogical, it is well possible to excite a pendulum to swing horizontally by the rhythmical application of vertical impulses.

Schlichting, H. Joachim: The sound of a bell within a wine glass
Naturwissenschaften im Unterricht- Physik 39/10, 20 (1991).

Commonly known, yet rarely understood, is the astonishing ability of wineglasses to produce sounds, which immediately remind their listeners of the pure tune of a bell. A detailed analysis of this phenomenon may well provide learners with an initial understanding of the basic principles of acoustics.

Schlichting, H. Joachim: Imploding beverage cans
Naturwissenschaften im Unterricht - Physik 39/10, 18 (1991).

Since the pledge on cans and other one-way containers has been introduced, flattened beverage cans have disappeared from German streets and schoolyards – the classroom analysis of an amazing physical way of crushing these aluminum containers is yet still an amazing demonstration of and an insightful example for the effects of sudden decompressions.

Schlichting, H. Joachim: Inertia's wile
Naturwissenschaften im Unterricht- Physik 39/10, 16-17 (1991).

A hands-on experiment to illustrate the most important aspects of inertia is presented . Subsequently, the applicability of this concept in numerous situations of everyday-life is demonstrated.

Schlichting, H. Joachim: Load transportation in a lemonade glass
Naturwissenschaften im Unterricht - Physik 39/10, 14 (1991).

A raisin that is thrown into a glass of lemonade initially sinks to the bottom. There, it gathers small bubbles of gas and transports them to the surface, from where it immediately returns to the ground to repeat its laborious exercise. The search for a physical explanation for the industry of the dried grape constitutes a motivating task for the physics classroom.

Schlichting, H. Joachim: A physical perspective on one of the most ingenious inventions of mankind: A sheave
Naturwissenschaften im Unterricht - Physik 39/10, 12 (1991).

A basic sheave serves as an example for the discussion of the fundamental principles of one of the most ingenious invention of mankind.

Schlichting, H. Joachim: Unexpected phenomena related to rotating objects
Physik und Didaktik 19/1,78 (1991).

Our common knowledge of rotation is surprisingly restricted. Consequently, its discussion in the physics classroom sometimes results in disorientation on the part of both, teachers and students. This paper presents a selection of related hands-on experiments, which put common knowledge and physical intuition to a test and may thereby contribute to the resolution of the confusion.

Schlichting, H. Joachim: Care about a glass of air?
Naurwissenschaften im Unterricht - Physik 38/1, 34 (1990).

Is it possible to pour a glass of air? The surprising answer is provided in this article.

Schlichting, H. Joachim: When air creates pressure... Hands-on experiments related to air pressure
Naturwissenschaften im Unterricht- Physik 38/5, 39 (1990).

"The ghost in the empty bottle" or "the conjuration of a flabby balloon" are only two of the amazing hands-on experiments which can be found in this compilation.

Schlichting, H. Joachim: The shortest way is not always the fastest one
Physik und Didaktik 18/3, 231 (1990).

It is demonstrated and explained why a ball which rolls down a longer path may nevertheless be faster than its companion on the shortest one.

Schlichting, H. Joachim; Rodewald, Bernd: Physical phenomena related to steam-jet boats
Praxis der Naturwissenschaften - Physik 39/8, 19 (1990).

The steam-jet boat, a popular tin toy from the years after the Second World War, may well become an object of physical education. Among its interesting physical facets explained in this paper are is the mechanics of its propulsion, the non-linearity of its oscillating thermodynamic engine and its underlying processes of self-organization.

Schlichting, H. Joachim: Complex toys
Physik und Didaktik 17/3, 231 (1989).

Many of the fundamental self-organizational processes of complex systems may well be analyzed and illustrated by the means of simple toys. The intention of this article is to propose ways to address the fascinating world of complex systems in physics classrooms.

Bachhaus, Udo; Schlichting, H. Joachim: The magic of the Hui-machine
Physik und Didaktik 16/3, 238 (1988).

The Hui-machine, a toy which is continuously rediscovered and renamed, fascinates by its almost magic behavior. The latter may yet be explained by simple physical principles.

Schlichting, H. Joachim: Hands-on experiments on phase transitions
Physik und Didaktik 16/2, 163 (1988).

Different examples of hands-on experiments involving phase transitions are illustrated and the universal physical principles involved in these processes are discussed.

Schlichting, H. Joachim: The mysterious gaze
Naturwissenschaften im Unterricht - Physik/Chemie 35/6, 35 (1987).

The eyes of a hollow mask appear to follow its observer. This amazing, sometimes frightening phenomenon is explained by the means of geometrical optics. The principles of inversion as well as the general reliability of human perception are discussed.

Schlichting, H. Joachim; Bachhaus, Udo: Chaotic toys
In: G. Marx (Ed.): Chaos in Education II. Vesprem (Hungary) 1987, pp. 58-63.

Physics education has hitherto largely overlooked the didactic potential of the classroom-analysis of the non-linear working principles of common toys. Some simple, easily available, and cheap toys may well be used for the demonstration of the ubiquitousness of non-linear processes of self-organization in our everyday lives. Arguably, an increased awareness of the latter will eventually facilitate a better understanding of many of the economical and ecological problems of the modern world.

Schlichting, H. Joachim; Rodewald, Bernd: Paper helicopter
Praxis der Naturwiss.-Physik 35/5, 30 (1986).

The aerodynamics of a paper helicopter are analyzed qualitatively and quantitatively. Furthermore, its exemplary value in view of the educational analysis of dissipative structures is elaborated.

Schlichting, H. Joachim; Rodewald, Bernd: The boomerang – a toy of remarkable flight qualities
Praxis der Naturwiss.- Physik 35/5, 18 (1986).

A simplified description of the underlying physical principals of the flight of the boomerang is presented. Despite being intended to be used in the German Sekundarstufe, this elementary model may well be extended into a consecutive quantitative description of this amazing device.

Schlichting, H. Joachim; Rodewald, Bernd: Ikarus' dream and aerodynamic reality
Praxis der Naturwiss.-Physik 35/5, 7 (1986).

The paper outlines a simple and easily accessible model of the flight of birds which constitutes the theoretical background of an in depth analysis of the anatomical prerequisites of natural flight. It will be shown that a detailed description of the wing beats used to generate propulsion is not essential for a general understanding of a phenomenon, the observation of which has inspired generations of mythologists, philosophers. scientists and engineers.

Rodewald, Bernd; Schlichting, H. Joachim: A catastrophic toy
American Journal of Physics 53/12, 1172 (1985).

A bird-in-the-shell toy can be considered a mechanical model of the physical concept of phase transitions. As such it constitutes a simple, cheap, and fascinating didactic device, which provides learners with valuable insights into phenomena otherwise accessible exclusively via  complex mathematical models.

Schlichting, H. Joachim: Learning mechanics with toys
In: P.L. Lijnse (Ed.): The many faces of teaching and learning mechanics; (Proceedings of the GIREP Conference on Physics Education 1984), S. 432, Utrecht (1985).

This paper provides an extensive list of useful toys for the physics classroom.

Rodewald, Bernd; Schlichting, H. Joachim: The pecking woodpecker – A toy which uses friction constructively
In: Scharmann et al. (Hrsg.), Vorträge der Frühjahrstagung der DPG, Gießen 1983, S. 50.

The pecking woodpecker constitutes an excellent example of a mechanism which uses friction constructively. Consequently, a kinetic analysis of the rhythmical way it moves along its stick provides students with valuable insights into the constructive aspects of friction.