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Running span

Symbols stream past and stop without warning; type the last few in order. More to keep, longer streams, faster, with no ceiling.

  • Memory
  • Timed
  • Endless levels

How it plays

Digits or letters appear one at a time. You are not told how many are coming. When the stream stops, type back the last few — the screen says how many — in the order they came.

Since any symbol might turn out to be among the last, the job is to keep only the newest few and let the oldest go each time a new one arrives. Levels add one to how many you keep, run the stream further past that number, and show each symbol for less time.

A typed answer earns partial credit for every symbol in its right place. Choosing instead shows the near misses: the window one step early, the start of the stream, the window reversed.

Keys

Space starts and skips ahead · 1–9 pick · Enter submits · Esc stops. On a phone, tap.

What it trains

This practises updating what you hold — keeping the newest and dropping the oldest. It improves this task; it is not, on the evidence, a route to general intelligence.

Learn

How to get better at running span: the method, the techniques, what each new level asks of you, and the traps the wrong answers are made of.

Your approach to each question

  1. Know your window before the stream starts: how many to keep is the same on every question at a level — it is on the Now line (“last 3 of up to 5”) and in the question after each stream.
  2. Load the first symbols as they come, saying them under your breath, until you hold that many: “4 7 2”.
  3. From then on, every new symbol pushes the oldest out. Say the new window each time — “7 2 9”, then “2 9 1” — and never hold more than the window.
  4. When the stream stops, the window you said last is the answer. Type it at once, in order, saying it as you type.

Techniques and tricks

  • Slide the window

    Treat what you hold as a queue: new symbol in at the back, oldest out at the front, every time. Say the whole window after each slide so its order stays fixed.

    e.g. Keeping 3 from 5 8 1 6 3: “5”, “5 8”, “5 8 1”, “8 1 6”, “1 6 3”. The answer is 1 6 3.

  • Say it with a beat

    From five to keep upwards, say the window in two groups with a pause between: “4 7 2 — 9 1”. A rhythm keeps the order when the window is too long for one breath.

  • Hold the places

    A typed answer earns credit for each symbol in its right place. If you lose one, type your best guess in its slot rather than leaving it out — a gap shifts every symbol after it out of place.

    e.g. The answer is 1 6 3 and you lost the 6: “1 0 3” keeps two places right; “1 3” keeps only one.

  • Never two the same in a row

    The stream never shows the same symbol twice running. If your window has 7 7 side by side, one of them is wrong.

  • Fold the last one in

    The stream stops without warning, so the last symbol is the one you are most likely to skip. Make the slide a reflex the instant each symbol appears, not when the next one comes.

As the levels climb

  • Three things rise in turn: one more to keep, less time per symbol, and a longer run past what you keep. The time falls from 1,000 ms a symbol to 470 ms; the run past the window grows from at most 2 extra symbols to at most 14.
  • How far the stream runs past the window is random each time, from none up to that most. Sometimes it stops exactly at the window and all of it counts — so start sliding the moment your window is full, and never wait for “the real start”.
  • The number to keep has no ceiling. Past six or seven, two groups with a beat, each said as a unit, are what hold the order.
  • At the fastest pace, each symbol gives you under seven-tenths of a second, gap included, to slide and say. Keep the inner voice short: say each window once, fast, not slowly and twice.

Traps to avoid

  • One step early: answering the window as it stood before the last symbol — 8 1 6 instead of 1 6 3. It happens when the stream stops and the last slide never happened. Fold the last one in.
  • Keeping the start: holding the first few, as in an ordinary span, and letting the end wash past. When choosing, the start of the stream is one of the wrong options for exactly this reason.
  • The order falling apart: saying only the new symbol instead of the whole window lets two neighbours swap or the window turn round. Both are among the wrong options when you choose.
  • Holding too much: trying to keep the whole stream “just in case”. It overloads and costs the ones that count; hold the window and nothing else.

How to practise

  • Set “Answer by” to “Choosing from options” for a session to see which near miss you make — one step early, the start, reversed or swapped — then go back to “Typing them”.
  • Change “Symbols” from “Digits” to “Consonants”, then to “Digits and consonants”. The mix is harder to say in rhythm, so the slide has to be cleaner.
  • Set “How many to keep at level 0” one below the window where you start to fail, so the opening levels build the slide reflex at a size you can manage.

Levels

Each question has a clock that comes from the work it asks for. There is no last level: at least one dial turns without end. Your level is judged on your last ten answers, every ten: 90% moves you up, below 80% moves you down, which holds most people near four in five right.

All of it is in the settings beside Start — how many answers a judgement looks at and how often it recalibrates, the thresholds, the time, which questions, how many options, and whether you see each verdict at once or review them together at the judgement. You can also jump to any level.

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