Level 5

It is interesting to contemplate an entangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us.

And now let me show in a figure how far our nature is enlightened or unenlightened.

Doubt has a bad reputation.

There is a stretch of my walk home that I could skip.

Marie Curie was born in Poland in 1867, when women there had few opportunities to attend university.

Long before vaccination, communities in parts of Asia and Africa practiced forms of variolation: introducing material from a person with smallpox in hopes of causing a milder infection and later protection.

An afternoon can hold only so much.

When we judge an unknown quantity, the mind reaches for a starting point and adjusts from there.

Earth stays warm enough for life partly because of gases in its atmosphere.

A star is not eternal; it is born, lives, and dies over spans that dwarf human history.

I once treated a free evening as a scheduling mistake.

When I began learning an instrument at forty, I discovered how much I disliked being a beginner in public.

Imagine a wooden ship kept in a harbor as a monument.

Suppose you were asked to design the rules of a society, including its laws and distribution of resources, but with one strange condition.

Being faster at two tasks does not necessarily mean it is best to do both yourself.

Imagine adding workers to a kitchen while keeping its floor space and equipment fixed.

A quantity can grow by adding the same amount at each step or by multiplying by the same factor.

How can someone send a confidential message without first meeting the recipient to agree on a secret code?

For thirty years Senora Bermudez wrote letters for people who could not, or would not, write their own.

Consider tin used in solder for joining metal parts.

New technology can expand production while reducing demand for older methods.

Gross domestic product, or GDP, measures the value of final goods and services produced within an economy during a period.

Take ten thousand grains of sand piled on a table.

In 1974 the philosopher Robert Nozick described a machine that could give you any experience you wanted.

A saying associated with ubuntu is often rendered in English as: a person is a person through other persons.

Around 1200 BCE, the eastern Mediterranean contained kingdoms linked by diplomacy, trade, and war.

About twenty years after conquering England, William I ordered a survey of land and resources.

In 2015, the Open Science Collaboration reported attempts to repeat one hundred studies from three psychology journals.

Halvard Sunde spent thirty-one years translating one poet.

A patient may report less pain after taking an inert tablet: one without the medicine's active ingredient.

Snow that falls on central Antarctica may remain instead of melting.

A bird that has been stung by a wasp may avoid another insect with similar yellow and black markings.

In 2007, John Maloof bought photographic negatives at a Chicago auction while researching a neighbourhood.

Suppose you pass a shallow pond and see a small child drowning.

In Aristotle's account, moral virtue develops through habituation.

The philosopher Iris Murdoch imagined a mother-in-law, M, who behaves faultlessly toward her son's wife, D, while privately finding her shallow, pushy, and beneath him.

In a machine shop, tolerance names an allowed range of variation.

After working on a painting all afternoon, an artist may begin to notice her intentions more readily than the marks actually on the canvas.

From 1889 until 2019, the kilogram was defined by the mass of a platinum-iridium cylinder kept near Paris.

Imagine a research team measuring a quantity for which a respected earlier result already exists.

The four-color theorem concerns maps drawn on a plane.

Continents appear fixed on a map, yet Earth's outer shell is divided into moving tectonic plates.

Suppose Mira must decide whether to approve a proposal.

Flying fish do not fly by flapping their fins like birds.

Conversation guides often treat silence as a gap that speakers should quickly fill.

Architect Leena Ortiz was hired to redesign a small apartment whose rooms had been divided awkwardly over decades.

As a student in Karnal, India, Kalpana Chawla watched aircraft and became interested in how machines move through air.

A team schedules two weeks to redesign a website.

An ordinary national passport is a document issued by a government to identify a person for international travel.

A young vine curled around a mango tree and climbed rapidly toward the sun.

A wampum belt is made from carefully shaped shell beads woven into patterns.

Suppose students rank schools, while each school has limited seats and a stated priority order.

A computer must coordinate countless changes in its circuits.

The DNA molecules in a eukaryotic cell are extremely long relative to the nucleus that holds them.

Can an all-powerful being create a stone so heavy that the being cannot lift it?

A wombat burrow is more than a hole deep enough to hide an animal.

A blank afternoon can feel like a failure of organization.

One mango remained on the kitchen shelf, fragrant and soft enough to eat that evening.

In 1948, writer James Baldwin left the United States for Paris.

People sometimes expect outcomes that are more favorable than the evidence supports: finishing sooner than comparable projects, avoiding setbacks, or succeeding at a difficult change.

A wallet found on a bus contains clues and private information.

At the entrance to an old granary stood a painted door.

During the Great Migration, from about 1910 to 1970, millions of Black Americans moved from the South to cities in the North, Midwest, and West.

Suppose a person chooses between a modest reward today and a larger reward next month.

A robot enters an unfamiliar warehouse.

An unglazed clay jar can cool the water inside it without a motor or a block of ice.

A dirt path crosses the corner of a public green.

In a managed park, a fallen trunk can look like unfinished work.

A coat hook is among the least impressive objects in a public room.

At first light, Noor found the fourth orange stake in an unexpected place beside the river path.

Maria Sibylla Merian learned about insects by keeping them close enough to watch.

A fox pauses beside a path and looks toward a hiker.

A repair log is a conversation between people who may never meet.

In the town granary, a brass Scale and a wooden Scoop worked beside the same bins.

In many medieval and early modern European towns, skilled trades were organized through guilds.

A machine's purchase price is only one part of what it costs to use.

An atomic clock does not count atoms, and its timekeeping does not depend on radioactive decay.

Michael Faraday entered science through a bookbinder’s shop rather than a university.

A single observation can fit more than one explanation.

To a swimmer at the surface, a coral reef may appear first as color and shape.

I used to hear repetition as a small failure of conversation.

Nara was hired to replace signs in a covered market above the harbor.

Mary Engle Pennington treated refrigeration as a continuous journey rather than a single cold room.

At a swap table, a mug may seem worth little until it is placed in your hand and called yours.

A lift, pumping station, or bakery mixer may be taken out of service while it still works.

Nilo promised the hill-town dancers a willow whistle before the lantern fair.

In the neighborhoods of Port of Spain, Trinidad, Carnival musicians spent decades turning available materials into new percussion.

At the end of a market day, three cooperatives compare their accounts.

A neighborhood team keeps an evacuation map in a shared digital project.

Every second, enormous numbers of neutrinos pass through your body and continue through Earth.

People often ask whether their work is meaningful, but the question can hide different demands.

On a rocky Pacific shore, mussels can crowd together so tightly that little bare stone remains.

A deadline can work like a lamp, revealing choices that were easy to postpone.

After the flood, Imani found a red kite tangled in a low tree in Block Seven's courtyard.

In 1921, Indian physicist Chandrasekhara Venkata Raman sailed across the Mediterranean Sea.

An improvement can feel enormous.

One spoken language may sound different across regions.

A raven found a silver button beside the road.

In June 1892, Māori leaders and representatives gathered at Waipatu in Hawke's Bay, New Zealand.

Suppose a basket of rice, rent, transit, soap, and medicine costs 100 currency units in one country and 200 in another.

A crop satellite does not see a field as a farmer does.

A low-energy ball cannot cross a hill; it rolls back.

Today’s decision can shape distant lives.

A horseshoe crab pushes across a tidal flat beneath a domed shell.

A speaker may insist, “My words were accurate; misunderstanding belongs to the listener.”

The stage door looked like studded oak.

Srinivasa Ramanujan filled notebooks with formulas in India, often recording results without the detailed proofs expected in university mathematics.

A student awaiting exam results may predict, “If I fail, I will feel terrible for months.”

A museum receives a figure said to come from a temple.

A tortoise carried herbs along a path curving around silver moss.

After World War II, Germany and Berlin were divided.

In a worker cooperative, worker-members collectively own and govern the enterprise.

A prosthetic hand can use motors to move fingers from user signals.

Two clocks can begin together, take different journeys, and disagree when reunited.