Collection
Mean, median, mode, box plot and levels of measurement: descriptive statistics to try out.
Apps
Building blocks on a weightless polystyrene board: it balances exactly above the mean, because the deviations Σ(xᵢ − x̄) cancel out. Drag the support, move the outlier, show the median and lever arms; plus the overall mean of two groups instead of the mean of the means.
StatisticsTry it
365 morning temperatures from Reutlingen cross a bridge from °C to °F one by one, or only their mean x̄ does. Both land at 47.12 °F: the arithmetic mean is invariant under linear transformations, m·x̄ + c. Kelvin as a second example, squaring as a counter-check where the shortcut misses.
StatisticsTry it
People line up by height; the middle one draws a chalk line on the wall: the median. Odd n (position (n + 1)/2) and even n (mean of the two middle values), position versus value, and why the line stays put when the tallest grows while the mean moves.
StatisticsTry it
The eye colours of 100 people sort themselves into four bars, brown 41, blue 33, grey 14, green 12: the tallest bar is the mode. Two counter-checks show why mean and median fail for nominal variables: averaging all colours gives a murky blob, and who stands at places 50 and 51 of the line-up depends on the arbitrary order of the categories.
StatisticsTry it
Mean growth rate the right way: production 1000, 1200, 1500, 900. Guess first, then three paths grow with a constant factor. The mean of the rates (+1.67%) ends at 1050.8, while production ends at 900. Only the geometric mean (−3.45% per year) hits the end value. Factors, product, n-th root, plus portfolio, inflation, bacteria and ±50%.
StatisticsTry it
Range, quantile, interquartile range and box-and-whisker plot: 40 gross salaries, scissors at the p quantile, cutting off the outer quarters. When the manager earning €40m joins, the range explodes and the IQR stays 32 k€. Then 40 body heights with histogram and box plot, whiskers from min to max or at most 1.5 · IQR with an outlier point.
StatisticsTry it
Rebuild 2.0 (preview): which constant value replaces them all? Returns, speed, savings plan, P/E and semicircle — AM, GM, HM in the replacement test, HM ≤ GM ≤ AM on the number line.
Data & decisionsTry it
Rebuild 2.0 (preview): location and spread, target parameters n, x̄, s, skewness and kurtosis via sliders.
StatisticsTry it
Rebuild 2.0 (preview): level of measurement as the set of admissible transformations — five statements hold or flip live, ladder of permitted statistics, sorting exercise with 19 variables.
Data & decisionsTry itCollections
Planning and steering projects: the iron triangle, stakeholders, network diagrams, earned value, schedule risk, team size, Kanban and waterfall against Scrum.
8 appsOpen collection
From sequences to loans: arithmetic and geometric growth, savings plans, annuities, compounding within the year and perpetuities.
11 appsOpen collection
Reading the traces: burial mounds in section, radiocarbon dating, settlements in the landscape and the tomb of Tutankhamun.
5 appsOpen collection
Why robot arms are heavy, how six axes guide a hand and how control holds the load.
4 appsOpen collection
Tables, keys, joins, groups and subqueries you can touch: how a database really reads.
7 appsOpen collection
Generative AI in strong images: what it can do, how it writes, why it convinces, how to use it well and where to take care.
7 appsOpen collection
Engine, brakes, high voltage, CAN bus and chassis: technology and diagnostics of the modern vehicle.
9 appsOpen collection
Heat in the city centre: heat islands, shade, trees and unsealing, using the old town of Reutlingen as an example.
5 appsOpen collection
Reading the small print, spotting subscription traps, placing risk figures and making texts understandable.
4 appsOpen collection
From equation to curve: initial values, linear equations, substitution and the worlds in which they apply.
7 appsOpen collection
From coordinates to the inverse: vectors, dot and cross products, linear equations and matrices in pictures.
12 appsOpen collection
Production principles, waste, one-piece flow, value streams, bills of materials and routing: how a factory is organised.
6 appsOpen collection
What the CRA requires of manufacturers: checking whether it applies, meeting reporting deadlines, keeping software bills of materials.
5 appsOpen collection
Reducing, common denominators, multiplying, dividing and mixed numbers: fractions step by step.
7 appsOpen collection
Proofs of special beauty to touch: Zagier's windmills, the museum guards and Buffon's needle.
3 appsOpen collection
How oscillations break down: coefficients, symmetry, phasor chains, the Gibbs phenomenon and the plucked string.
7 appsOpen collection
What happens inside the machine: objects, methods, operators, slicing and sorting in Python, visible step by step.
9 appsOpen collection
From the Patent Motor Car to the Z3: famous machines and experiments cut open in 3D.
11 appsOpen collection
Keyboard, intervals, scales, chords, the circle of fifths and groove: music theory you hear and play.
9 appsOpen collection
How sound is made and shaped: synthesizers and samplers, envelopes and overtones, waveforms and timbre, voice and orchestra, room acoustics and sound scenography — all audible in your browser.
16 appsOpen collection
Staging space, sight, light, sound and paths: visitor flows, showcase lighting, room acoustics, sound islands, projection mapping and the pavilions of world expos to try out.
15 appsOpen collection
Mathematical questions open for decades, for which an AI model proposed solutions in 2026, as interactive apps: understand the problem, experience the result.
32 appsOpen collection
From neurons and gradients to transformers, RLHF and agents: machine learning you can touch.
44 appsOpen collection
DNA, replication, transcription, translation and cell division as explorable 3D models.
24 appsOpen collection
Perspective, ornament, structure and space: how art and architecture work with mathematics.
21 appsOpen collection
Hyperloop, autonomous vehicles, warehouses and conveyors: logistics as interactive simulation.
17 appsOpen collection
Heart, eye, voice, skeleton and nerves: the human body in 3D, layer by layer.
10 appsOpen collection
Monty Hall, Simpson, Berkson and base rates: where intuition fails us with numbers.
14 appsOpen collection
Planets, stars, black holes and space probes: the cosmos to explore.
10 appsOpen collection
Light switches for nerve cells, a telescope made of ice, mirror-image chemistry and interest rates: the 2026 Nobel Prizes to try out.
8 appsOpen collection
Planted participants, smoke in the room, one dollar for a lie and experimenters who are themselves the subjects: famous social psychology experiments to try yourself.
5 appsOpen collection
Relations, classes, orders, bijections, different infinities and topology: mathematics as the science of structure, hands-on.
11 appsOpen collection
Riemann, P vs NP, Poincaré and other great questions of mathematics, made tangible.
16 appsOpen collection
Counting, arithmetic and shapes: maths for beginners, playful and clear.
6 appsOpen collectionWant to use these apps in your courses? Let’s find out what works for you.
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