For parents, teachers & club leaders
Teach the satellite internet class
A practical guide to preparing the experiments, checking the calculations and pitching the work across Grade 7 to Grade 12.
Before the first session
- Choose the four- or eight-week plan below. Read Lesson 1 and prepare a small encoded picture of your own.
- Check the mathematics your learners have. Every lesson splits its calculations into a core set needing arithmetic, ratio and substitution, and a deeper set assuming trigonometry, logarithms or Newtonian mechanics. Doing only the core set is a complete course.
- Gather the core materials, and make sure every learner has a calculator with sin, cos and a logarithm. Print one mission notebook each, or copy the prompts into an ordinary book.
- Prepare table or floor space for the moving-satellite and packet games. A solo learner can move all the counters.
- Explain the final demonstration in week one, and keep the same model and the same records as it grows.
Choose your course length
One 90-minute session each week. Eight weeks gives time to measure, calculate and redesign; four weeks keeps the same eight lessons and the same physics, with the quantitative work concentrated into fewer, longer blocks.
8 weeks · build, calculate, improve
- What a message actually is — Information · binary encoding · error control · systems
- Putting information on a wave — Electromagnetic spectrum · modulation · bandwidth · signal-to-noise
- Why the relay stays up — Gravitation · circular motion · orbital period · scale
- The geometry of being in view — Spherical geometry · elevation angle · footprint · handoff · Doppler
- Closing the energy budget — Solar constant · cosine law · energy storage · thermal radiation · propulsion
- Where the delay actually comes from — Packet switching · propagation · queuing · throughput · latency budget
- Designing under constraint — Link budget · requirements · shared spectrum · orbital debris · tradeoffs
- Defending the result — Systems integration · error analysis · reproducibility · bounded claims
4 weeks · the essential mission
Week 1 · Information, and the signal that carries it
15 min: measure a picture in bits and compare parity with triple repetition; 20 min: encode and transmit an 8-bit frame by flashlight over three matched trials; 20 min: change one factor and retest; 20 min: calculate c = fλ for the flashlight and for a 12 GHz downlink; 15 min: apply the Shannon–Hartley ceiling to one channel and explain why the repetition code costs rate.
Week 2 · Orbit, and the geometry of being in view
15 min: derive v = √(GM / r) and evaluate it at 550 km; 15 min: build one consistent scale model and mark both shells; 25 min: run the 12-step visibility model on paper and on screen; 20 min: calculate γ, footprint radius and pass duration at 25° minimum elevation; 15 min: compare slant range at zenith and at the edge, and convert the ratio to decibels.
Week 3 · Power it, then route the message
15 min: size a battery from the solar constant, the eclipse fraction and depth of discharge; 15 min: test the cosine law at three panel angles, or complete the paper budget; 25 min: run the packet model under normal, congested and failed conditions; 20 min: separate propagation, queuing and serialisation in the measured delay; 15 min: compare a fibre route with a vacuum laser relay over the same distance.
Week 4 · Design it, defend it
15 min: write a measurable target with its failure condition; 20 min: build and run a baseline; 20 min: change one variable, retest and record honestly; 15 min: quantify one shared-sky cost — brightness in magnitudes or decay time against altitude; 15 min: demonstrate under a drawn challenge card; 5 min: write the bounded claim your evidence supports.
A predictable 90-minute rhythm
| Minutes | Purpose |
|---|---|
| 10 | Opening puzzle and prediction |
| 15 | Read and explain the physics |
| 30 | Build and investigate |
| 25 | Measure, calculate, change one thing, retest |
| 10 | Independent explanation and notebook |
In the four-week route, use its session-specific timings instead. Grade 7–8 learners should do every build and every core calculation, and may be given derived values such as γ rather than deriving them. Grade 9–12 learners should do the deeper tasks, which carry the transferable skills: deriving a relation, converting a ratio to decibels, and testing how sensitive a conclusion is to an assumption. The electronics kit is optional throughout.
What each lesson assumes
| Lesson | Core tasks need | Deeper tasks need |
|---|---|---|
| 1 · What a message actually is | Powers of 2, percentages | Exponential growth, rate arithmetic |
| 2 · Putting information on a wave | Scientific notation, c = fλ | log₂, decibels, small-angle beam spread |
| 3 · Why the relay stays up | Square roots, substitution | Algebraic derivation, Kepler III, small-angle approximation |
| 4 · The geometry of being in view | Degrees to radians, arc length | Sine rule, inverse cosine, decibels |
| 5 · Closing the energy budget | Unit conversion, cos θ | Fourth roots, the rocket equation, logarithms |
| 6 · Where the delay comes from | Division, rates | Solving a linear equation for break-even |
| 7 · Designing under constraint | Reading a logarithmic scale | Deriving a dB constant, multi-variable tradeoff |
| 8 · Defending the result | Tabulating with units | Latency budget, sensitivity analysis |
Common misunderstandings to listen for
- Bits are a description of information. What crosses the gap is a changing physical quantity; the protocol supplies the meaning, and it has to exist at both ends.
- Protection is never free. Parity costs one bit in nine and only detects an error; triple repetition costs two bits in three and corrects one error per triple.
- A brighter transmitter is not the answer to a slow link. In C = B·log₂(1 + S/N) a hundredfold power increase roughly doubles capacity, while doubling the bandwidth doubles it outright.
- Formulas take orbital radius r; maps quote altitude h. Using 550 km where 6,921 km belongs gives an answer wrong by a factor of three, not by a few percent.
- Gravity still acts in orbit — 8.31 m/s² at 550 km, about 85% of its surface value. Forward velocity is not an outward force cancelling it.
- Higher orbits are slower, not faster, because v = √(GM / r). Learners usually expect the opposite.
- Geometric visibility is necessary but not sufficient. A visible satellite still needs capacity, a working beam and a path onward to a ground station.
- Sampled coverage is not continuous coverage. If the usable arc 2γ is narrower than the angular spacing between satellites, a gap exists whether or not the sampling caught it.
- Panels answer “how fast can we collect?” and batteries answer “how much did we store?”. In eclipse, twice the panel area collects twice nothing.
- Watts and watt-hours are different quantities. Most failed energy budgets in Lesson 5 are unit errors rather than physics errors.
- Latency and throughput are independent measurements and can move in opposite directions. “Fast” is one word doing the work of two.
- An improved model result supports a bounded claim naming its rule, its condition and its observation window — never a promise about actual Starlink performance.
Final demonstration rubric
Mark each criterion 0–3. Use the profile to decide what to revisit; a completed model on its own does not establish understanding.
| Criterion | Evidence to look for |
|---|---|
| Science | Correct account of signals, orbit, visibility geometry and energy, with the governing relation named in each case. |
| Quantitative work | Calculations carrying units throughout, orbital radius distinguished from altitude, watts from watt-hours, latency from throughput. |
| System | An end-to-end route with its return journey and a clear function for every component. |
| Evidence | Baseline and revised results under an identical stated rule, the failure condition named, and uncertainties given for hand-timed values. |
| Limits and consequences | A specific limitation of this model, a bounded claim rather than an overclaim, and a reasoned shared-sky tradeoff. |
0 = absent or substantially incorrect; 1 = partial, needing substantial prompting; 2 = mostly correct with a small gap or prompt; 3 = accurate and independently supported. Total: 15 possible points. A low criterion calls for a focused retry rather than a lower overall mark.
Checking the work
Every lesson carries a revealable checkpoint and a fully worked example; ask for an attempt before either is opened. Two errors are worth catching on sight because they are large rather than subtle: using altitude where a formula wants orbital radius, which is wrong by a factor of three, and mixing watts with watt-hours, which is wrong by whatever the time interval happens to be.
For the final demonstration, change a condition and ask for a prediction before running the test, then review prediction, records and revised explanation together. Written and spoken explanations need human review. Accept any design whose reasoning matches its stated rules and its recorded measurements — including one that failed, was changed, and was re-tested honestly.
Read further
Technical context checked October 20, 2026. The orbital, geometric and energy figures in this class are calculated from published constants and stated assumptions and rounded for teaching; they describe idealised models, not measurements of any operating system. The activities, fictional records and teaching sequence are independently authored, and this class is not affiliated with SpaceX or Starlink.
- Starlink: technology — the real system and its equipment.
- NASA: What is a satellite? — satellite and orbit background.
- IAU Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference — reflected sunlight, satellite trails in astronomical images, and radio interference. Co-hosted by NSF NOIRLab and the SKA Observatory.