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Span (unit)

Span (unit) is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Span (unit) rather than just read about it. In short: A span is the distance measured by a human hand, from the tip of the thumb to the tip of the little finger. In ancient times, a span was considered to be half a cubit.

Span (unit) — main illustration
Span (unit) — illustration

Key takeaways

  • Span (unit) belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Span (unit) to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Span (unit) from memory before moving on to harder problems.

Reference excerpt

A span is the distance measured by a human hand, from the tip of the thumb to the tip of the little finger. In ancient times, a span was considered to be half a cubit. Sometimes the distinction is made between the great span or full span (thumb to little finger) and little span or short span (thumb to index finger, or index finger to little finger).

History Ancient Greek texts show that the span was used as a fixed measure in ancient Greece since at least archaic period. The word spithame (Greek: "σπιθαμή"), "span", is attested in the work of Herodotus in the 5th century BC; however, the span was used in Greece long before that, since the word trispithamos (Greek: "τρισπίθαμος"), "three spans long", occurs as early as the 8th century BC in Hesiod.

Size of the span

Biblical usage

1 span = 9 inches = 22.86 cm

Chinese usage In China and Chinese cultured countries, a span (一拃) refers to the distance between the tip of the thumb and the tip of the outstretched index finger (sometimes middle finger), and typically measures 15–20 cm (5.9–7.9 in).

Arabic usage In Arabic, the analogue of the great span is the šibr (شبر). It is used in Modern Standard Arabic and classical Arabic, as well as in modern-day dialects.

Slavic usage

In Slavic languages, the analogue of the span is various words derived from Proto-Slavic *pędь (Bulgarian педя, Polish piędź, Russian пядь, Serbian педаљ, Slovenian ped, etc.). In various Slavic languages it is the distance from the tip of the thumb to the tip of the little finger or index finger. For example, Slovenian velika ped = great span (23 cm (9.1 in)), mala ped = little span (9.5 cm (3.7 in)); Russian piad = 4 vershoks = 17.8 cm (7.0 in).

African usage In Swahili, the equivalent of the great span (thumb to little finger) is the shubiri or shibiri while the little span (thumb to forefinger) is the morita or futuri.

Hungarian usage In Hungarian, the span, or arasz, is occasionally used as an informal measure and occurs in two varieties: measured between the tips of the extended thumb and index finger, it is kis arasz (the "small arasz"); between the tips of the thumb and little finger, it is nagy arasz (the "large arasz"). The term "arasz," used by itself without a modifier, is usually understood as referring to the "large arasz," i.e., to the "span."

South Asian usage In Hindi-Urdu and other languages of Northern India and Pakistan, the span is commonly used as an informal measure and called bālisht (Urdu: بالشت, Hindi: बालिश्त). In Bengali, it is called bighāt (বিঘত or বিঘৎ). In Marathi, it is called weet (वीत). In Nepal, where this method of measurement is still used in informal context, a span is called bhitta. In Tamil, it is called saaN.

Southeast Asian usage In Southeast Asia, the span is used as an informal measure. In Malay and Indonesian, it is called jengkal. In Thai, it is called khuep. In Filipino, it is called dangkal.

Mongolian usage The span is commonly used as a traditional and informal measure in Mongolia, where it is called tuu (төө). Depending on the use of index or middle finger and the placement of the thumb, the span is named differently as tuu (төө) and mukhar tuu (мухар төө) etc.

Portuguese usage

The old Portuguese customary unit analogue to the span was the palmo de craveira or simply palmo. 1 palmo de craveira = 8 polegadas (Portuguese inches) = 1/5 varas (Portuguese yards) = 0.22 m (8.7 in)

See also Anthropic units Hand (unit) List of human-based units of measurement List of unusual units of measurement Units of measure

Notes

References Lyle V. Jones. 1971. “The Nature of Measurement.” In: Robert L. Thorndike (ed.), Educational Measurement, 2nd ed. Washington, DC: American Council on Education, pp. 335–355.

Illustrations

Span (unit): Some hand-based measurements, including the great span (4)
Some hand-based measurements, including the great span (4)

Worked examples

Example 1 — a first encounter with Span (unit)

Start with the simplest possible case. Write down what Span (unit) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Span (unit) before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Span (unit) ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Span (unit)

In research
Span (unit) appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Span (unit) in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Span (unit) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Human-based units of measurement, Imperial units, Units of length, so understanding it makes those chapters shorter.
In everyday life
Look for Span (unit) outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Span (unit) in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Span (unit) means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Span (unit) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Span (unit) in simple terms?

A span is the distance measured by a human hand, from the tip of the thumb to the tip of the little finger. In ancient times, a span was considered to be half a cubit.

Why does Span (unit) matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Span (unit)?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Span (unit).

Tags

  • Human-based units of measurement
  • Imperial units
  • Units of length

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