This post covers two related pieces of work: a paper on DIY smartphone experiments for stellar formation, submitted to Astronomie+Raumfahrt (co-authored with Alexander Küpper); and a board game, “Staub und Sterne” (Dust and Stars), designed for use in secondary school physics by Miriam Küpper and Alexander Küpper.

The Curriculum Problem

The 2019 revision of the NRW Gymnasium physics curriculum for Sekundarstufe I requires students to be able to describe, in broad outline, the typical stages of stellar evolution. This can be new territory for teachers whose training did not include astrophysics; the curriculum requirement itself does not establish how common that training gap is.

More fundamentally: stellar evolution is a topic where the usual experimental approach does not work. You cannot compress an interstellar gas cloud in a classroom. You cannot observe a star form in real time. The timescales involved are tens of millions to billions of years; the spatial scales are measured in light-years and astronomical units. The experimental toolkit that works for optics, mechanics, and even much of electromagnetism simply does not apply.

This creates a genuine pedagogical challenge. ROSE survey items show substantial but population- and item-dependent interest in astrophysical topics, and stellar evolution involves curriculum-relevant concepts such as gravity, pressure, energy, and radiation. But the standard path from “concept” to “experiment” to “understanding” is not available in the usual form.

Two approaches are described here. One uses what students do have — smartphones and household materials — to model the physics of stellar formation through analogy. The other accepts that some physics is better learned through structured play, and designs accordingly.

DIY Experiments for Stellar Formation

The physics of star formation starts with an interstellar gas cloud and the competition between gravity and pressure. A cloud collapses when gravity wins: specifically, when the cloud is massive enough (or cold enough) that gravitational attraction overcomes the thermal pressure of the gas. The idealised Jeans analysis expresses one gravitational-instability threshold; real molecular clouds also involve turbulence, magnetic fields, rotation, cooling, geometry, and external forcing.

The qualitative version is accessible to secondary school students: a dense, cold, massive cloud is more likely to collapse than a diffuse, hot, small one. Once an unstable region collapses, gravitational contraction can continue while pressure, rotation, magnetic fields, turbulence, and energy transport modify the dynamics.

Two DIY experiments were developed to give students a physical encounter with the key concepts, using materials that can be assembled at home or in school without specialist equipment.

Experiment 1: Compression and heating. Sufficiently rapid gas compression can raise temperature. This can be measured with a suitable external sensor and an apparatus designed for the pressure involved. Smartphones rarely expose an ambient-temperature sensor to phyphox; their internal readings usually describe the device, not the gas. The stellar connection is adiabatic heating during contraction, although a protostar also transports and radiates energy and is not a sealed syringe.

Experiment 2: Self-reinforcing compression. A simple model of the positive feedback loop in gravitational collapse: a weighted ball in a flexible container, which compresses a small spring or air cushion. The more the ball compresses the cushion, the further it falls. Students can explore how changing load alters an equilibrium. It is a force-feedback analogy, not a self-gravitating system and not a measurement of the Jeans criterion; no tabletop cushion compresses indefinitely.

Both experiments were designed around accessible materials. Any pressure vessel, syringe, weight, or heated component still needs an apparatus-specific classroom risk assessment. Compatible external sensors can provide quantitative data; availability is not guaranteed by possession of a smartphone.

Why Stellar Evolution Is Hard to Experiment With

A methodological note worth making explicit: the shift from direct experiment to analogy experiment to board game is not a retreat from rigor. It is a recognition that different kinds of physical and conceptual content require different pedagogical approaches.

For exoplanet detection, we can build a genuine analogy: the physics of a planet blocking a star’s light and a ball blocking a lamp’s light are structurally identical. The analogy experiment produces data whose interpretation follows the same logic as the real scientific data.

For stellar evolution, the analogy is weaker. The compression of a gas syringe models one aspect of the collapse (temperature increase) but not the self-gravitating dynamics, the hydrostatic balance that emerges as the protostar evolves, or the nuclear ignition that defines entry onto the main sequence. Radiation pressure is important in massive stars but is not the universal agent that halts collapse. No tabletop experiment captures the whole process.

This is important to tell students: the experiment models this aspect, and not those aspects. It also omits rotation, magnetic fields, turbulence, and energy transport. Making the model limits explicit is part of the scientific literacy the unit is supposed to develop.

“Staub und Sterne”: A Board Game for Stellar Evolution

The board game “Staub und Sterne” (Dust and Stars), designed by Miriam Küpper and Alexander Küpper, takes a different route to the same content.

Games have been used in physics education in all phases of a lesson: as entry points (introducing a topic without immediately constraining it to a specific physical question), as vehicles for content acquisition, and as reinforcement and assessment tools. For stellar evolution specifically, the argument for a game is strong: the content involves a branching process with multiple pathways depending on a single initial parameter (mass), it is cyclic (the remnant of stellar death seeds the gas cloud that forms the next generation of stars), and it is inherently dynamic — the drama of a supernova is hard to convey through a diagram but easy to convey through play.

The target audience is years 7–8 (or year 8–9 depending on the school’s internal curriculum placement). The learning objectives:

  • Describe the stages of stellar evolution as a function of mass
  • Name the possible end states (white dwarf, neutron star, black hole) and the stellar paths that lead to each
  • Describe stellar evolution as a cyclic process: the gas cloud produced at the end of a star’s life can, under the right conditions, seed the formation of new stars

The game “Staub und Sterne” (the name translates as “Dust and Stars”) has players navigating a star through its lifecycle, with the key branching decision determined by the star’s initial mass. A low-mass star follows one path; a high-mass star follows another. Both paths end in a stellar remnant and a dispersed gas cloud — raw material for the next cycle.

The design uses cooperative or competitive play and immediate feedback with the aim of supporting engagement. The cited presentation documents that design; it does not measure flow, attention, or learning relative to conventional lessons.

A Note on What Experiments Cannot Reach

There is a broader point here that the exoplanet posts sidestep because the experiments for exoplanet detection are so unusually good. For most astrophysics — stellar evolution, galactic dynamics, cosmology — there is no analogy experiment that captures the full physics. The observable has been observed, the theory has been developed, but the pedagogical problem of how to give students a physical encounter with that knowledge remains genuinely difficult.

Games, simulations, interactive visualisations, and structural analogies all have a role. Each of them is a partial solution; none of them is what a well-designed experiment is. Knowing which approach fits which content, and being honest with students about the limits of the model you are using, is part of what physics teaching requires.

The experiments described in this post are a start on one small part of that problem.

The exoplanet experiments from the same project are described in the astro-lab@home, Hunting Exoplanets with Your Phone, and Fremde Welten posts.

The misconceptions students bring to stellar evolution — about the Sun, gravity, nucleosynthesis, and the language of astronomy — are documented in detail in Please Stop Saying the Sun Is on Fire, written as a companion to the September 2020 teacher training session that motivated much of this work.

Astronomy and education literature checked through 2026-07-11.

References

Spicker, S. J., & Küpper, A. (submitted). Einfache DIY-Experimente zum Verständnis der Sternentstehung für den Physik- und Astronomieunterricht sowie zu Hause. Astronomie+Raumfahrt im Unterricht.

Küpper, M., & Küpper, A. (2022). Sternentwicklung spielerisch verstehen: Konzeption eines Brettspiels für den Physikunterricht der Sekundarstufe I. Presentation at AG Lehrerfortbildung, Universität zu Köln.

Elster, D. (2008). Was interessiert Jugendliche an den Naturwissenschaften? VFPC Verein zur Förderung des physikalischen und chemischen Unterrichts.

MSB NRW (2019). Kernlehrplan für die Sekundarstufe I — Gymnasium in Nordrhein-Westfalen: Physik. Ministerium für Schule und Bildung NRW.

Ward-Thompson, D., & Whitworth, A. (2011). An Introduction to Star Formation. Cambridge University Press.

Changelog

  • 2026-07-11: Bounded the Jeans and classroom analogies, corrected smartphone temperature-sensor and stellar-pressure claims, added apparatus safety limits, and separated the board-game design from unmeasured learning outcomes.