Virtual Tours

A four-slot bench. Place the blocks, read the Python each one writes, then train and test a machine that really learns - 55 guided activities.

Walk through nine galleries of real artefacts with a guide, from Harappa to 1947, or pick a chapter tour for your class. At every stop, find the detail on the photograph, then read what it tells us and what it cannot.

Drop beads into glass rooms and watch ten collapse into one — carries, exchanges, ×10 shifts, lakhs, crores and decimals, all the same law.

Real denominations in a finite till with availability-aware change-making; unit prices, discounts, GST rates and profit as exact arithmetic; a week of demand against a stock plan; simple interest; a cash-book that closes.

A dynamic construction engine: exact line-circle-circle intersections in canonical order, re-evaluated as free points move; goals judged over the whole figure and at twelve random drags before they snap.

Sampling without replacement from a seeded school; standard error measured by repeated surveys; Census 2011 states; Tufte lie factor, pictogram squaring and dual-axis crossings computed from the chart settings.

Coins and dice tumble for real; a log-axis chart watches ten thousand of them settle onto ½ and 1/6 — then a hidden bag dares you to infer its contents from draws alone.

Six stations: zoom until any curve straightens, forge the formulas geometrically, ride a car whose odometer IS the integral, drag real geometry to its optimum, and sail boats on a differential equation.

02:40, every room full, the bell still ringing. Find the move - then meet the guest list that cannot be housed at all.

Play 10 instruments, compose on a step sequencer, and explore music theory interactively.

A daily-step pot model: soil water as a fraction of capacity with drainage above field capacity by soil type and absolute evapotranspiration from leaf area, light and heat; germination on moist warm days; light-limited sugar production feeding height and leaf area under a pot-limited ceiling; etiolation, chlorosis, wilting and root rot as state; phototropic lean with pot rotation; a short-day photoperiod flowering rule and fruit set; a fair-test checker; and a persistent plant advanced on the real clock between sessions.

A daily crop model run live against seeded season weather with an 80 %-reliable three-day forecast: growing-degree-day phenology with dry-sown seed that waits for moisture and seedlings that die in a false start, radiation-use growth over a canopy-cover light interception, a root-zone water balance with soil-specific field capacity, drainage and runoff, a leached and mineralised nitrogen pool, logistic weeds suppressed under a closed canopy, pest–enemy dynamics with a seeded pressure and a seasonal window, waterlogging damage, post-maturity drying, shattering and rain losses, and per-hectare economics. Losses to weeds, pests and nitrogen are measured by replaying the student's own action log with each factor switched off; ten-year and three-season scenes run the same model by rule.

A paintable 7×24 timetable, four plates and a water count driven through a five-minute physiological trace: two-process sleep pressure with a carried sleep debt and light-delayed onset, gut absorption at each plate's rate cap and time constant, a lagged insulin response with rate-of-rise sensitivity, liver glycogen with gluconeogenic fallback, hourly water losses with kidney conservation and thirst-driven drinking, MET-based energy expenditure, and nightly stamina, stress, immune-defence and mood tallies with a Wednesday germ exposure. Every readout and all six dials are measured from the traced week.

Strip skin, muscle and bone off a real scanned body, open the heart, and follow food, breath or blood through it.

An actual human cell imaged by electron microscopy — orbit it, cut it open, isolate each organelle.

Real optics: the field shrinks as you go up, the depth of field collapses, and the 100x is useless without its drop of oil.

You never walk anywhere: dispatches come to your war table inside a lymph node. Press a WANTED poster from a captured fragment, find the one recruit tag whose notch fits it, then choose artillery or assassins - and a wrong order is carried out and fails in front of you.

Susceptible and resistant populations with lag, logistic growth on depletable nutrient, whole-cell mutation from accumulated divisions and a fitness cost; Hill-type antibiotic kill above strain MICs with first-order drug decay and eight-hourly dosing; host nutrient replenishment and immune clearance; Poisson plate counts with dilution; D- and z-value heat kill for a vegetative cell and a spore; log-reduction hand-washing; and a thirty-day ward whose failures seed later arrivals unless isolated.

Eight-species food web with logistic producers under seasonal forcing and a drought factor, Holling type II consumers with diet preferences, trophic efficiency, mortality and self-crowding, stepped monthly in sub-steps; removals, reintroductions, an invasive competitor with a control; trophic pyramid, keystone search by secondary extinctions, carrying capacity with overshoot, toxin concentration by diet and efficiency, calendar-month peaks and a stability index — all measured against the untouched forest.

Cut a stem open, pick one vascular bundle, and travel down into it — then ride the water up a xylem vessel and the sugar through a real pierced sieve plate.

A brokerage floor of flower stalls and their couriers: read each signboard's terms, read each order chit, and close the deal. A match rides from anther bay to stigma desk to the ovule counter and stamps a fruit; a mismatch comes back with the clashing clause circled.

You are not a visitor, you are the sound. Choose a pitch and a loudness, then get carried with no stops while your own form is transformed six times - and your pitch decides where on the basilar membrane the ride ends.

Fly into a leaf, ride an electron down the thylakoid, and find out what is really limiting the rate

Real Visible Human anatomy: every chamber and valve, a continuous beat, and blood you can follow drop by drop.

Real Visible Human lungs that never stop breathing — follow the airway from the voice box down every branch to the air sacs, and watch oxygen cross into the blood.

Ride a red cell from the air in your lungs to a working muscle; watch a wound seal and an infection get cleared.

The Allen Human Brain Atlas reference brain, published structure by structure — isolate any lobe, the hippocampus or a single thalamic nucleus, and ride a signal from eye to hand.

Gametes enumerated per locus with probabilities, linked loci in coupling or repulsion with a recombination fraction, a Punnett square as the outer product, phenotypes by dominance, blending, codominance, X-linkage and a lethal; litters drawn by seeded random gamete sampling with lethal loss; tallies, deviation, recombinant fraction and a chi-square against expected shares; a pedigree whose inferable genotypes are derived from real ones.

Individual-based population genetics: sixteen additive diploid trait loci plus a marker locus, environmental noise, fitness-proportional parent draws, Mendelian segregation with per-copy mutation, optional assortative mate choice among six suitors, and frequency-dependent two-niche payoffs. Heritability is read as R/S from truncation breeding and checked against Va/Vp counted from the birds; stabilising, directional and disruptive selection, drift at N = 10 versus 1000, founder draws, mutation-selection balance for a harmful recessive, island divergence and reunion, and a moving-background melanism run are all measured from the stepped generations.

Fly along a real double helix and zoom from a whole body down to single atoms — written for three grade bands

A coupled physiology stepped per minute: ventilation gated by brainstem drive, muscle and energy; oxygen and CO₂ against supply and activity demand; gut absorption, insulin-gated uptake, liver glycogen and a fasting floor; urea production and renal clearance; heat balance with fever set-point; infection growth against immune killing; marrow production against red-cell lifetime; energy from oxygen, fuel and pumping; a brain with thresholds — and a timeline of when each part stopped.

Switch between globe and flat maps, compare thematic layers, search places and practise geography.

A three-minute film you ride as the drop — each stage happens on screen first and is only named afterwards.

Six full-screen chapters through clouds, thunderstorms and a tropical cyclone. Change the conditions, compare fair tests and keep a local field journal.

One river, source to sea — the V-shaped valley and waterfall up top, meanders and ox-bow lakes across the plain, then the delta it builds.

ERA5 reanalysis for six cities through 2025; wet bulb by Stull; readings checked against the record; forecasts scored by MAE and Brier against persistence and climatology; monsoon onset read off the rain.

A sample state machine on real rates: 25 °C/km geotherm, Athy compaction, crystal size from cooling time, rounding with distance, Ferguson-Church settling for the jar test; density, hardness and fizz read off the state.

Natural Earth coastlines through real projection formulas; Tissot from the numerical Jacobian; areas by spherical excess and shoelace; great circles and loxodromes; a Copernicus-DEM sheet with marching-squares contours, bilinear heights and sampled sections.

The Earth's crust in motion — plates colliding, the Himalaya rising, trenches, earthquakes and the Ring of Fire.

Rewind 250 million years and watch the continents ride their plates to where they are today

Crust, mantle and core — read the planet's layers from the earthquake waves that cross it

Watch a new ocean open at a mid-ocean ridge and follow the youngest rock on Earth

One plate bends beneath another and carves the deepest trenches on the planet

India meets Asia — an ocean closes and the world's highest mountains rise

Stretch and squeeze rock layers to see how faults, folds and block mountains form

Every eruption leaves another layer — build cones, lava plateaus and flows

Follow a grain of sand from mountain to sea through valleys, meanders and deltas

Moving ice carves U-shaped valleys, cirques and moraines

Wind shapes dunes, mushroom rocks and the desert horizon

Waves build beaches and carve cliffs, arches and sea stacks

Follow a raindrop underground into caves, stalactites and sinkholes

See heat, water and life break rock into soil — and when a slope gives way

Read a landscape's hazards and resources, then decide where a town should grow

A 22-day survey from Terai marsh to cold desert. Climb too fast and altitude sends you back down.

Helm a Roman merchantman by the Periplus. Miss the Hippalus wind and the voyage simply does not happen.

A brass-railed map table at the Monsoon Bureau. Turn the year, warm the seas, watch both branches sweep.

Eighteen worlds in one place — drag the timeline and the atmosphere, oceans, continents and life all change around you.

Seven fibres with tenacity, elongation, regain, crimp, lustre, stiffness, shrink and wrinkle parameters plus dye-class affinities and burn behaviour; a twist-multiplier utilisation curve for yarn strength; weave-dependent jamming, tensile, tear-sharing, bending and thickness factors; cover-factor breathability, trapped-air warmth, regain-driven absorbency, relaxation shrinkage, fastness-driven wash fading — a testing bench that computes every property from the construction.

A three-node thermal model (pot and water, food surface, food core) with latent-heat boiling pinned at a pressure- and sugar-dependent boiling point, surface-moisture-gated Maillard kinetics, Q10 starch and protein cooking, egg-white and yolk set points with carry-over, casein coagulation below pH 4.6 in hot milk, first-order vitamin C decay plus leaching, a yeast rate curve with a death temperature, temperature-dependent bacterial doubling, syrup boiling-point elevation, and a plate builder on per-serving nutrient values.

Text analytics counted from the draft as it stands — sentence splitting, a syllable counter, Flesch reading ease, a passive-voice detector, adverb and echo counts, adjacent-sentence cohesion, the topic sentence by shared words — and a reader model that spends attention word by word and gives up when it runs out; ten drafts with a brief each, all verified solvable.

Formant and noise synthesis for fourteen English sounds, an FFT ear measuring level, voicing, spectral centroid and the first two resonances, tuned to the machine's own vowels; microphone input classified live; blending as timed cues.

Stems and rules only: plurals and obliques from gender and ending class, marked adjectives, habitual and future conjugation with auxiliaries, perfective participles with vowel- and consonant-stem shapes and irregular जाना, the ergative ने with object agreement; student choices assembled and held against the rule-built sentence.

Words as IAST sound strings; external and internal sandhi applied at the seam by rule (savarṇa-dīrgha, guṇa, vṛddhi, yaṇ, pūrvarūpa, ayādi, visarga, ścutva, jaśtva, anusvāra), ṇatva through the word, a-stem declension derived from stem + ending pieces, and a Devanagari writer that renders results rather than looking them up.

Tap a letter, see where it is made in the mouth, trace it, and meet three words that start with it

A garden, a home, a school — name everything, then make it one, two or many

Drop picture cards on the kāraka wheel — who, what, where — and watch the sentence build itself

One crow or two? Today or yesterday? Turn the knobs and the whole story rewrites its endings

Type Hindi or English and see the Sanskrit derived rule by rule, with every sūtra named

Type any Sanskrit and read it back — split the sandhi, name every form, decline and conjugate anything

Your class's Sanskrit chapters as guided stops, Class 6–9 or Class 10–12

A live dictionary drawn as a star map: each word's meanings, examples and pronunciation, with its similar, nearby and opposite words orbiting it. Jump to a neighbour and your path stays in the sky; meaning trails ask you to reach a target word in as few jumps as the shortest known route.

Food-table compositions per 100 g; reagent responses saturate with starch, protein, fat and reducing sugar; energy by 4/4/9; adulterants answer chemically — density, fizz, dye, magnet, float.

Not a tour of a refinery - you are one hydrocarbon chain inside it. Build your own chain carbon by carbon, call the tray you think will catch you, then lose all control as the column sorts you by your own boiling point.

Electrode potentials drive everything: acid rates, displacement free energy (ΔG° = −nFE°), water and steam; Ellingham lines decide the furnace, Faraday the cell; rust rates by water, air, salt, coat and couple.

Dalton to Schrodinger, each model shown with what it could not explain - plus the gold foil, the oil drop and the photoelectric bench that forced the change.

Zoom from a drop of water to a proton — then build elements, ions and bonds

Valency rules on every bond; a 3-D minimiser with covalent-radius springs and VSEPR domain repulsion (lone pairs weighted); angles, shape names and dipoles read from the coordinates.

Hundreds of molecules with thermal walls (flux-weighted re-emission), a massive piston driven by the momentum they deliver, hard-sphere collisions on demand; every law is read off the records.

All 118 elements in 3D — rebuild the table by any property and open any atom's shells

Night shift on the ammonia loop. Temperature and pressure pull against each other, exactly as they do in industry.

One map with seven places to explore: the playground, roads and rails, a building site and fair, power and magnets, the harbour, the spaceport and the physics lab. Pick a place and step into any of its nineteen tours; your progress is shared with each tour's own page.

Poles as 1/r² sources, wires by Biot-Savart, coils as rows of wires, iron by induced poles - and the plotting-compass method done step by step, by hand.

Eight stops on electromagnets: count the clips a coil on a nail can lift, swing a compass by reversing the current, and drop steel into a skip by switching off. A stop ticks only when the run shows it.

A playground roundabout with a rider who lets go along the tangent, a 20 m big wheel with a bathroom scale under one seat, and a test car on a 25 m bend in the dry, the wet and on ice. F = mv²/r, measured.

A steel A-frame swing set with a child, an adult or an empty seat. Pull it back, let go and time five swings. Change the chain, the rider, the push and even the planet, and see T = 2π√(L/g) at work.

Eleven stops on particles and heat, one experiment each: a chamber of 250 simulated molecules, a bath that melts ice a cup of tea cannot, spoons in hot soup, a rail joint in the sun and a tethered balloon.

Six stops on wind and solar power, one experiment each: measure a 90 m rotor at 5 and 10 m/s, run it into a storm, then tilt a solar row and race a sun tracker through a clear day, all measured.

Eleven stops on orbits around a real-scale Earth: fire a cannon from a 408 km mountain, weigh an astronaut in orbit, time satellites high and low, find escape speed. A stop ticks only when the flight shows it.

Eleven stops on light as a message from atoms: a prism spectroscope with NIST line spectra, a Bohr model of hydrogen, and a rooftop 1 m telescope that reads a star's temperature off Planck's curve.

Nodal analysis behind a board built for Class 6: drag a wire, the bulb lights; short the cell, it runs hot; two cells and the filament goes.

Seven stops on electricity, one experiment each: 12 V lamps on a shed board that glow by their real power, a 30 km line that loses a fifth at 11 kV, a house battery bank. A stop ticks only when the meters show it.

Finite-difference conduction, a buoyancy-driven fluid solver for convection, line-of-sight radiation and an enthalpy model for melting - every pixel is a cell of the solver.

Every graph comes from the tape, not the simulation: read every fifth dot for the smooth line, every dot for the noise. Then draw a v-t graph and the cart follows it.

Seven stops on stopping a car: a second of thinking, then the brakes. Make it rain, snow and fog and watch the orange and red strips on the road stretch. A stop ticks only when the run shows it.

Twelve experiments from umbra to chromatic aberration, on a rail where every ray is traced through real glass and nothing is drawn in.

Five stops on light at a surface, one experiment each: a straw in a 60 cm tank, a D-block on a degree disc read by detectors, a 12 mm light pipe you can kink. A stop ticks only when the reading shows it.

Eleven stops on friction, one experiment each: send a child down a 30° slide, tilt a chute until a boot slips at μ = tan θ, time a sled in the rain. A stop ticks only when the run shows it.

Hydrostatics done honestly: the level follows the volume plus what the blocks displace, jets obey Torricelli, and every block settles where Archimedes says.

Seven stops on falling, one experiment each: pump the air out of a 12 m tube, stream a parachute behind a 45 m drop, push blocks down a 60 m lane. A stop ticks only when the measurement shows it.

Eleven stops on Newton’s laws, one experiment each: hitch on wagons, halve the speed, let a loose wagon roll on with nothing pushing it, push two trolleys apart. A stop ticks only when the run shows it.

Twelve stops on pressure and floating: lower pieces into fresh water, sea water and brine, load a barge to its Plimsoll line, and feel the squeeze grow as a sub dives. Each stop ticks on a measurement.

You are one joule of reservoir water. Every gate takes an honest toll, and conservation becomes an account you survive.

Eleven stops on hitting hard: find the swing that just breaks a brick wall, stretch a 50 km/h stop from 12 ms to 80 ms, and make coupled wagons stop dead. Every force and time comes out of the collision itself.

Seven stops on rocket thrust, one experiment each: fire the engine in a vacuum, turn the flow up until push beats weight, swap a blunt nose for a pointed one, escape the Moon. A stop ticks only when the flight shows it.

Eleven stops on one ride: set the lift hill and the second hill, fill the seats, stiffen the grease and loop the loop, with the energy books on every run. A stop ticks only when the measured ride shows it.

Mechanical advantage measured, not stated: load over effort off a balance, hand distance over load distance off the tapes, and efficiency as their ratio with friction included.

Thirteen stops on a building site: hang a pallet of bricks on 1 to 6 ropes, find the steepest ramp a worker can manage, and fit a winch motor. A stop ticks only when the gauge or the clock shows it.

Thirteen stops on turning forces: slide riders out along a seesaw, lift a sandbag with three kinds of lever, load a crane's concrete, climb a hill in the right gear. A stop ticks only when the run shows it.

Real Web Audio: the scope and spectrum are read off the speaker, not redrawn from the input. Draw a wave, build a square from sines, time thunder and an echo, hear the Doppler shift.

Open a real DC motor on the bench, pull every part out, then rebuild it and make it spin

A real stiffness solve on every click: tension blue, compression red, Euler buckling for long struts, progressive collapse when a member goes, and a budget that punishes overbuilding.

Per-nucleus stochastic decay with a tube that hears a fraction plus background; cross-section fission on a lattice; the real D-T reactivity curve; energies from real atomic masses.

Poisson + Scharfetter-Gummel drift-diffusion on the painted bar; built-in voltage, depletion width, currents and gain all read off the solution; band diagrams live.

Board a spacecraft and travel out past every planet to the icy edge. Nothing is arranged — the planets are placed by solving Kepler's equation from JPL orbital data.

Meeus Sun and Moon, JPL Keplerian planets, HYG stars to magnitude 5.5; altitude and azimuth from your latitude and sidereal time; sunrise found by watching the Sun cross the horizon.

One console, no walking. Poll the stations, hold for weather, then ride the ascent through every staging event.

No route and no Next button - one blank almanac leaf, four masonry instruments each sighted its own way, and a sinking-bowl water clock that only runs forwards, so a sighting window you miss stays missed.

Travel through Earth, India and world history. Compare overlapping reigns, trace battles and discover poets, reformers and their famous works.

Excavate three fictional sites with a context-aware engine. Brush, record and lift each find; compare materials, order deposits and later cuts, and connect cautious interpretations to evidence. Save or export your field notebook locally.

Three guided journeys through Mohenjo-daro, archaeology, and Seals & Signs — explore 419 catalogue glyphs and experiment with an explicitly invented two-way converter.

Three foremen will take an apprentice, in any order you like: pour a lost-wax bronze you are allowed to spoil, weigh the rival answers to how the capstone rose, and clear a Srivijaya manifest customs can bounce. The olai keeps failures struck through, not erased.

Built to the published measurements, with the real relief photographs readable panel by panel - then a time dial from Ashoka's brick stupa to the 1818 ruin to today.

Walk a timeline corridor from the Janapadas through the Mahajanapadas to the Maurya and Gupta empires.

You never walk anywhere - the whole lab is one scribe's desk, where you strike an Ashokan edict into stone stroke by stroke and dispatch it to a real find-site that can send it back, plus a side desk for stamping Megasthenes BELIEVE or DOUBT.

Petitions arrive at your desk in Akbar's court; route each to the right office and the Mughal administrative machine teaches itself.

Vijayanagara at its height — the gem bazaar, the Stone Chariot and the singing pillars — then the same ground today, read like a detective.

Depth is the interface: the only movement is a winch riding a cut shaft, and finds are dated by which stratum you shelve them in - until a relocated Ashokan pillar shows that made-when and buried-when are different questions.

1857 to 1947, gate by gate — then march beside the Dandi column to the sea

Explore Ellora's Cave 16 — the excavated courtyard, Nandi pavilion, soaring temple and carved stories, with a guided journey through its architecture.

Stand at the fork in Frost's autumn wood, walk either road to where it bends, and read the lines that argue with the famous ending.

The Globe, 1599. You are the book-holder behind the wall, running the show on cues while the yard watches.

Keep a temple storehouse's records in 3200 BCE. Count the goods off the dock yourself, then watch each technology break under the audit it cannot answer - loose tokens anyone can palm, a sealed bulla you must smash to read - until your own hands press the first writing.

Kalki's story as a place: stalk the hundredth tiger the Maharaja never quite kills

Homer's Odyssey as a 3D voyage — Troy, the Cyclops, Circe, the Sirens, and the long road home to Ithaca.

Stand in one person's moment, pull the ring, and ten thousand lives arrange themselves into the pattern - then swap between seven thinkers' lenses over the same unchanging scene.

Sit as the Speaker, the Prime Minister, the President and the Chief Justice. Every power is Article-cited, and using one brings the other organs' reply straight to your desk.

The real calligraphed manuscript, page by page - Raizada's hand and Nandalal Bose's illuminations - then step through a page into the world it describes.

Twenty kilos of Nashik tomatoes, one dispatch desk, a spoilage clock - and a bill spike showing who got which rupee.

You are drawn by lot at dawn and hold one Athenian civic day in your own hands - bronze pinakion, juror's staff, the secret ballot, the ostrakon. The day only runs forwards, so the one way to meet a case again is to wake and be drawn again.

Be the coin. Wage, deposit, reserve rule, loan, till - each hand stamps you, and the stamps are the ledger.

A 5 × 5 town with elevations, occupancies and values; river stage against embankment height and block elevation, rain against drain capacity; depth–fatality and depth–damage functions, evacuation from lead time against drill-shortened evacuation time, shelter dryness and reach; PGA attenuation and lognormal fragility by building class with retrofit medians; occupancy by time of day; relief person-days from affected × days flooded — every outcome run against the unprepared baseline.

Evidence as items with a kind, an admissibility rule and a likelihood ratio; a posterior of guilt multiplied from prior odds over admitted items, each weakened by cross-examination effects; standards of proof by case type; a ten-stage procedure order, an Article 20–22 rights list, a bail rule (bailable → right; else flight, tampering or grave-and-strong), a proportional sentencing range from base × factors, and a judgment checker that rejects reliance on excluded evidence, the wrong standard or a finding the scales do not support.

A body stepped one second at a time: first-order heart-rate lag with a post-exercise floor, exponential lactate above a threshold with a sourness integrator that makes the legs give, glycogen burned as the square of demand, sweat and cardiac drift, muscle temperature and a sprint that depends on it; a Banister fitness–fatigue block and a stress–recover–grow strength model. Every readout comes from the trace.

A sagittal chain of thirteen segments with Dempster masses and joint limits, posed by dragging; forward kinematics, the floor as the lowest point, contacts, a centre of mass and its margin over the base of support; eight asanas as lists of measured checks, a breath-driven resonant heart-rate model (RSA peaking near six a minute), and a sun-salutation breath rule derived from each pose's measured chest openness.

A 3-D ball-flight integrator with quadratic drag, Magnus lift from a spin vector and a bounce model, shared by cricket, football, basketball and athletics; rules as geometry — six, hoop, wall and goal, leg before, offside, penalty reach — and a long-jump model that trades run for lift; optima found by flying, not by formula.

A monthly funnel model — organic and saturating paid visitors, price-dependent sign-up, quality-dependent conversion and churn, referral, a decaying product — with runway, break-even, default-alive, CAC, LTV, an investor's disclosed valuation rule and a market shock with a pivot, all measured by running the months forward.

An agent market: sixty buyers with private values, forty growers with private costs. Demand and supply are head-counts at each price; the clearing price, a tâtonnement auctioneer, tax incidence, shortages under a ceiling, surpluses under a floor, arc elasticity and a monopolist's deadweight loss are all counted from the agents.

A month of real transactions posted to a ledger; the beam's tilt is computed from the two pans' totals, never from an answer key. Wrong-side, wrong-account and compensating faults injected into the books; gross and net profit and a balance sheet closed from the postings.

A thirty-day simulation with rent, Friday wages, materials on supplier credit, sales on customer credit, capacity and overtime, an overdraft with interest and a mid-month materials shock; accrual profit beside the nightly bank balance; every optimum found by re-running the month.

A quarterly macro model with a two-quarter rate lag and a one-quarter spending lag, a Phillips curve with adaptive, half-anchored expectations, Okun's law, public debt, a zero lower bound and seeded shocks; a squared-deviation loss, sacrifice and on-target quarters are summed from the model's own states.

Instrumented bubble, selection, insertion, merge and first-pivot quicksort with replayable event traces; linear, binary and hashed look-ups with probe counts; a face-down comparison oracle against the ⌈log₂ n!⌉ bound; log-log growth fits; a hand-run Dijkstra checked pick by pick; BFS, Dijkstra and A* on a paintable weighted grid with expansions counted.

Stand inside a network that is actually learning — signals cross the layers and the error falls

Say a word and watch it become a picture — then watch a machine read that picture back

A differential-drive robot with lagging, mismatched, battery-scaled motors; a cone sonar with specular loss and stray echoes; footprint line sensors; wheel encoders that slip on dust; a front bumper. Rule ladders and step sequences run at a chosen loop rate; every judgement is measured from the simulation.

Millisecond-timed trial machines for simple, choice, Stroop and Posner tasks with anticipation and lapse exclusion; an adaptive digit-span staircase; free-recall serial-position scoring by thirds; method-of-adjustment illusion measurement; log-ratio anchoring analysis; mirror-tracing with slip counting; and a one-up two-down staircase for the JND at two standards — all statistics computed live from the student's own data.

Logistic age curves for A-not-B search, liquid conservation, false belief and perspective taking; a U-shaped overregularization curve; softmax Kohlberg level shares; Ainsworth reunion behaviours with a classification rule; Steinberg's peer effect; age-weighted self-description categories — every readout a seeded cohort drawn from the curve, so transition ages are measured by the student, and the timeline is assembled from those same curves.

A little kathputli stage in a courtyard at dusk, with a girl and a boy puppet on their strings and a row of animals watching from a charpai. Bring one puppet to the other and both bow with a big NAMASTE; a flower, a tap on empty hands or a bump bring THANK YOU, PLEASE and SORRY, and three picture cards start a tiny play.

A whitewashed courtyard wall waits for the festival, with pots of red, yellow, blue and green and a low table of stamps: a cut bhindi, a potato half, a leaf and your own thumb. Dip, press, and drag a finger left to right along the dotted lines, and the wall fills with star-flowers, soft blobs, veined leaves and marigold garlands.

A hand cart at the lane corner, piled with fruit and sabzi just delivered, a tap dripping beside it and a monkey watching from the wall. Wash each thing under the tap, sort fruit from sabzi into the two baskets, and count three bananas into the monkey's hand.

One cutaway house shared by an elephant family and a mouse family, with a long table under the window, two charpais at the back and a water pot by the door. Bowls, chairs, blankets and beds come in two sizes: a child fits each to the right animal, gives one plate to every guest and fills the pot cup by cup, until everyone is fed and tucked in and the lamp dims.

A small farm shed and yard in the morning light: a cow and her calf, a hen and two chicks, a goat and her kid, a dog asleep by the gate. Touch an animal to hear it and see its word, carry the right food from the trough, and lead each wandered baby back to its mother until the sun climbs and the yard rests.

Six vehicles wait in a yard where a road, a river and the sky meet. Tap one to hear it and see its word, then drag it to the road, the river, the rails or the sky: the right place takes it in and it joins a parade that never stops.

A dhol under a neem tree, with a basket of things beside it. Tap a banana and the drum plays its three beats, one lantern each; drum them back yourself, and later find everything that starts like BALL.

Dusk at the edge of a village: a bird, a fish, a bee, a dog, a rabbit, a frog and a cow are out, and it is time to go home. Touch an animal to hear its name, take it to its nest, pond, hive, kennel, burrow or shed, then sort everyone into two glowing hoops until night falls and the fireflies come out.

One sunny room seen from the doorway, and a kitten that hides in it: UNDER the charpai, BEHIND the matka, IN the almirah. The room says where, the child looks there, and then hides the ball where the kitten asks.

A bazaar stall under a striped awning, with a brass tarazu that tips toward whatever is heavier: balance a pumpkin against tomatoes, one at a time, until the beam hangs level and the stall bell rings. Beside the stall, five clay matkas wait by a wall to be stood on the chalk line from shortest to tallest.

An evening mela with five stalls, one for each festival the neighbours keep: Diwali, Holi, Eid, Christmas and Pongal. Light the diyas, throw the gulal, serve one bowl to every friend, dress the tree and draw the kolam; when all five stalls are alight the sky fills with fireworks and lanterns.

A flat rooftop on a Sankranti morning: a pinwheel in a pot, a kite by its spool, clothes on the line, a paper boat in a tub, a dandelion in a crack, a balloon on a pump and a wind sock on a pole. Press and hold the sky and the wind blows across the roof; the child never sees the air, only what it moves.

A big garden seen from behind the gate, with stepping stones, a well, a mango tree, a pond with a duck and a swing. One instruction at a time, in words and as an arrow, walks a small explorer to a hidden chest; then the child lays arrow tiles on the stones and a puppy follows them exactly.

A carpenter's bench with three letter blocks spelling CAT and a picture frame that shows what the word says. Swap one block from the shelf to make HAT, HOT, HOP and on up the ladder; the bird climbs a rung for every new word and rings the bell at the top.

A writing desk by an open window, with crayons, letter tiles that say their sounds, an envelope and a sheet of stamps. Draw a picture, spell your name and one word by its sounds, then fold, stamp and post the letter, and watch a card from Nani fly back in.

A doorstep on Diwali evening: bowls of coloured powder, a tray of petal, dot and leaf tiles, and a squirrel who likes patterns. Lay a few tiles in the rule slot and the rangoli border repeats them by itself; the squirrel guesses your rule, a sorting tray waits at the side, and when the border is full and the tray is sorted the diyas light.

A toy train pulls into a little hill station with some animals already aboard and the number on its engine, and every passenger the child taps onto the next wagon makes the count carry on from there. Trace each wagon's numeral in a sand tray, and when all ten are aboard the whistle blows and the train goes round the hill to start again.

A small house cut open in the evening: a tap drips into a bucket, a fan turns in an empty bedroom, the TV flickers at no one, the kitchen bucket is about to spill, and Nani reads under her lamp. Tap each room, switch off what nobody is using, and watch the tank stop falling and the moon come out.

A rooftop weather corner where the sky shows its signs first: dark clouds piling up, a blazing sun, clothes beginning to flap. Take out an umbrella, a hat or a kite, watch a day pass in seconds as rain fills the gauge, the sun dries the puddle and the wind lifts the kite, and pack the school bag for summer, monsoon and winter.

Open the colourful Little Worlds selection page and choose from all 14 pre-primary adventures.

Follow pictures into first words.

First… next… and then something lovely.

Find the beat in what comes next.

Small pieces. Wonderful possibilities.

One for you. One more for the basket.

Look, listen and notice the world.

A tiny seed. A very big adventure.

Splish, splash. What happens next?

Many kinds of families. Many ways to help.

Meet the people who help our days go well.

Stop together. Look together. Walk together.

A gentle journey from breakfast to bedtime.

Listen closely. The garden is singing.

Meet a colour. Make another.

A Scratch-style stage: paint or pick sprites, give them costumes and sounds, and snap event, motion, looks and pen blocks into games and animations. Start from an example or a blank stage.

Drag parts onto the board and wire them up. Simulate lights what really carries current, a missing resistor burns an LED out, and any part you pick shows the milliamps flowing through it.

Build an Arduino sketch from blocks, then switch to the real .ino code and edit it. Plug in a board and watch its serial output in a monitor and a live plotter.

Drop shapes, glue them together, and turn any shape into a hole that carves the rest live. Every selection shows its size and volume in centimetres; export an STL when it's ready to print.

Real Python, running in your browser: write in the editor, run it in the console, and load example programs to take apart and change.

Paint on a pixel grid with a twelve-colour palette, save what you make to your creations, and export it as a PNG.

Mine with the right tool, craft at a table, smelt in a furnace, farm wheat and build — then wire redstone into lamps, doors and logic gates, because a torch goes out when its block is powered.

A pot as 24 rings with height, radius and wall thickness under volume conservation; a collapse rule against wall thickness and height above, a load-over-strength slump rule that weakens with water, centrifugal rim flare, drying, and a kiln that bursts wet clay, cracks uneven walls and shrinks sound work by a tenth; capacity integrated from the hollow.

Rectangles on a 600×800 sheet measured for WCAG contrast, type-size hierarchy, shared edges and centre lines, margins, sampled whitespace, a luminance-weighted centroid, distance to rule-of-thirds crossings, characters per line, hue palettes and harmony, overlap and containment; ten briefs verified to fail as given and pass with a model layout.

A 160×120 cell model of paper: water spreading to drier neighbours and carrying pigment, pigment drifting through standing water, downhill runs past the paper's holding capacity, evaporation fixing pigment, surface charcoal moved only by rubbing, wax blocking water; subtractive RYB colour; spread radius, run length, mixing, hue, darkness and smoothness measured on the grid.