The güiro, a musical instrument traditionally made from a dried and hollowed gourd, is thought to have originated with the Taíno people of Puerto Rico. Players use a wooden stick to scrape along ridges cut into the side of the gourd, creating sounds that are highly ______blank: the sounds produced by güiros can differ based on the distance between the ridges, the types of strokes the player uses, and the thickness of the gourd.

Text 1

For decades, bluegrass musicians have debated whether their genre should exclude influences from mainstream genres such as rock. Many insist that bluegrass is defined by its adherence to the folk music of the US South, out of which bluegrass emerged. Such “purists,” as they are known, regard the recordings of Bill Monroe, which established the bluegrass sound in the 1940s, as a standard against which the genre should still be measured.

Text 2

Bluegrass isn’t simply an extension of folk traditions into the era of recorded music. In reality, Bill Monroe created the bluegrass sound in the 1940s by combining Southern folk music with commercial genres that had arisen only a few decades before, such as jazz and the blues. Since bluegrass has always been a mixed genre, contemporary bluegrass musicians should not be forbidden from incorporating into it influences from rock and other mainstream genres.

Cats can judge unseen people’s positions in space by the sound of their voices and thus react with surprise when the same person calls to them from two different locations in a short span of time. Saho Takagi and colleagues reached this conclusion by measuring cats’ levels of surprise based on their ear and head movements while the cats heard recordings of their owners’ voices from two speakers spaced far apart. Cats exhibited a low level of surprise when owners’ voices were played twice from the same speaker, but they showed a high level of surprise when the voice was played once each from the two different speakers.

In West Africa, jalis have traditionally been keepers of information about family histories and records of important events. They have often served as teachers and advisers, too. New technologies may have changed some aspects of the role today, but jalis continue to be valued for knowing and protecting their peoples’ stories.

While researching a topic, a student has taken the following notes:

• Species belonging to the Orchidaceae (orchid) family can be found in both tropical and temperate environments.
• Orchidaceae species diversity has not been well studied in temperate forests, such as those in Oaxaca, Mexico.
• Arelee Estefanía Muñoz-Hernández led a study to determine how many different Orchidaceae species are present in the forests of Oaxaca.
• Muñoz-Hernández and her team collected orchids each month for a year at a site in Oaxaca.
• Seventy-four Orchidaceae species were present at the site.

When they were first discovered in Australia in 1798, duck-billed, beaver-tailed platypuses so defied categorization that one scientist assigned them the name Ornithorhynchus paradoxus: “paradoxical bird-snout.” The animal, which lays eggs but also nurses ______blank young with milk, has since been classified as belonging to the monotremes group.

The following text is from Edith Nesbit’s 1902 novel Five Children and It. Five young siblings have just moved with their parents from London to a house in the countryside that they call the White House.

It was not really a pretty house at all; it was quite ordinary, and mother thought it was rather inconvenient, and was quite annoyed at there being no shelves, to speak of, and hardly a cupboard in the place. Father used to say that the ironwork on the roof and coping was like an architect’s nightmare. But the house was deep in the country, with no other house in sight, and the children had been in London for two years, without so much as once going to the seaside even for a day by an excursion train, and so the White House seemed to them a sort of Fairy Palace set down in an Earthly Paradise.

While researching a topic, a student has taken the following notes:

• Oracles of the Pink Universe was a 2021 exhibition at the Denver Museum of Art in Colorado.
• It featured eight artworks by South African artist Simphiwe Ndzube.
• One of these works is a painting titled Assertion of Will.
• Assertion of Will depicts three standing figures.
• The figures wear clothing made of fabric pieces stitched to the painting’s canvas.

The 1967 release of Harold Cruse’s book The Crisis of the Negro Intellectual isolated him from almost all other scholars and activists of the American Civil Rights Movement—though many of those thinkers disagreed with each other, he nonetheless found ways to disagree with them all. He thought that activists who believed that Black people such as himself should culturally assimilate were naïve. But he also sharply criticized Black nationalists such as Marcus Garvey who wanted to establish independent, self-contained Black economies and societies, even though Cruse himself identified as a Black nationalist.

In the 1950s, a man named Joseph McVicker was struggling to keep his business afloat when his sister-in-law Kay Zufall advised him to repurpose the company’s product, a nontoxic, clay-like substance for removing soot from wallpaper, as a modeling putty for kids. In addition, Zufall ______blank selling the product under a child-friendly name: Play-Doh.

Classical composer Florence Price’s 1927 move to Chicago marked a turning point in her career. It was there that Price premiered her First Symphony—a piece that was praised for blending traditional Romantic motifs with aspects of Black folk music—and ______blank supportive relationships with other Black artists.

Philadelphia’s Black Pearl Chamber Orchestra, founded by Jeri Lynne Johnson, performs classical music, from well-known compositions by Beethoven to contemporary works by Jessie Montgomery. For the orchestra’s iConduct! program, Johnson invites community members to learn some basic elements of conducting and then experience conducting the Black Pearl orchestra themselves.

Particle physicists like Ayana Holloway Arce and Aida El-Khadra spend much of their time ______blank what is invisible to the naked eye: using sophisticated technology, they closely examine the behavior of subatomic particles, the smallest detectable parts of matter.

While researching a topic, a student has taken the following notes:

• The Philadelphia and Lancaster Turnpike was a road built between 1792 and 1794.
• It was the first private turnpike in the United States.
• It connected the cities of Philadelphia and Lancaster in the state of Pennsylvania.
• It was sixty-two miles long.

Scientists studying Mars long thought the history of its crust was relatively simple. One reason for this is that geologic and climate data collected by a spacecraft showed that the crust was largely composed of basalt, likely as a result of intense volcanic activity that brought about a magma ocean, which then cooled to form the planet’s surface. A study led by Valerie Payré focused on additional information—further analysis of data collected by the spacecraft and infrared wavelengths detected from Mars’s surface—that revealed the presence of surprisingly high concentrations of silica in certain regions on Mars. Since a planetary surface that formed in a mostly basaltic environment would be unlikely to contain large amounts of silica, Payré concluded that ______blank

In Jane Austen’s novel Mansfield Park, an almost imperceptible smile from potential suitor Henry Crawford causes the protagonist Fanny Price to blush; her embarrassment grows when she suspects that he is aware of it. This moment—in which Fanny not only infers Henry’s mental state through his gestures, but also infers that he is drawing inferences about her mental state—illustrates what literary scholar George Butte calls “deep intersubjectivity,” a technique for representing interactions between consciousnesses through which Austen’s novels derive much of their social and psychological drama.

In 2007, computer scientist Luis von Ahn was working on converting printed books into a digital format. He found that some words were distorted enough that digital scanners couldn’t recognize them, but most humans could easily read them. Based on that finding, von Ahn invented a simple security test to keep automated “bots” out of websites. The first version of the reCAPTCHA test asked users to type one known word and one of the many words scanners couldn’t recognize. Correct answers proved the users were humans and added data to the book-digitizing project.

Text 1

Stage lighting theorist Adolphe Appia was perhaps the first to argue that light must be considered alongside all the various elements of a stage to create a single, unified performance. Researcher Kelly Bremner, however, has noted that Appia lacked technical expertise in the use of light in the theater. As a result of Appia’s inexperience, Bremner argues, Appia’s theory of light called for lighting practices that weren’t possible until after the advent of electricity around 1881. 

Text 2

Adolphe Appia was not an amateur in the practice of lighting. Instead, it is precisely his exposure to lighting techniques at the time that contributed to his theory on the importance of light. When working as an apprentice for a lighting specialist in his youth, Appia observed the use of portable lighting devices that could be operated by hand. This experience developed his understanding of what was possible in the coordination of elements on the stage.

Although military veterans make up a small proportion of the total population of the United States, they occupy a significantly higher proportion of the jobs in the civilian government. One possible explanation for this disproportionate representation is that military service familiarizes people with certain organizational structures that are also reflected in the civilian government bureaucracy, and this familiarity thus ______blank

While one requires oxygen and one does ______blank and anaerobic respiration are both forms of cellular respiration—that is, they are processes by which cells break down glucose to use as energy.

For centuries, the widespread acknowledgment of the involvement of the cerebellum—a dense brain structure in vertebrates—in coordinating motor control in humans has hindered recognition of other possible functions of the structure. Neuroscience research from the last two decades now suggests that the cerebellum regulates emotion and social behavior, and recent research by Ilaria Carta and colleagues has identified a pathway connecting the cerebellum to a center for motivation and reward processing known as the ventral tegmental area (VTA).

Michelene Pesantubbee, a historian and citizen of the Choctaw Nation, has identified a dilemma inherent to research on the status of women in her tribe during the 1600s and 1700s: the primary sources from that era, travel narratives and other accounts by male European colonizers, underestimate the degree of power conferred on Choctaw women by their traditional roles in political, civic, and ceremonial life. Pesantubbee argues that the Choctaw oral tradition and findings from archaeological sites in the tribe’s homeland supplement the written record by providing crucial insights into those roles.

Although it’s clear that Mars once had liquid water on its surface, astronomers have debated whether the evidence of ancient water reflects a prolonged phase of warm, wet conditions—the so-called wet and warm scenario—or a brief period of melting in an otherwise consistently frozen environment. Researchers Benjamin T. Cardenas and Michael P. Lamb recently added to this debate by using data from NASA and the Mars Orbiter Laser Altimeter to map the topography of what is now a large basin in Mars’s northern hemisphere. Cardenas and Lamb concluded that the wet and warm scenario is likely correct.  

While researching a topic, a student has taken the following notes:

• Freddie Wong (born 1985) is a director and special effects artist from the United States.
• He is best known for the action-comedy web series Video Game High School (VGHS).
• VGHS premiered in 2012 on RocketJump, a YouTube channel that Wong cocreated.
• The series was celebrated for its inventive video game–centric world and high-quality special effects.
• VGHS was nominated for a Producers Guild Award for Outstanding Digital Series.

To better understand the burrowing habits of Alpheus bellulus (the tiger pistol shrimp), some studies have used resin casting to obtain precise measurements of the shrimps’ burrows. Resin casting involves completely filling an empty burrow with a liquid plastic that hardens to create a three-dimensional model; however, recovering the model inevitably requires destroying the burrow. In their 2022 study, Miyu Umehara and colleagues discovered that an x-ray computed tomography (CT) scanner can accurately record a burrow’s measurements both at a moment in time and throughout the entire burrow-building process, something that’s impossible with resin casting because ______blank

On sunny days, dark rooftops absorb solar energy and convert it to unwanted heat, raising the surrounding air ______blank a light-colored covering to an existing dark roof, either by attaching prefabricated reflective sheets or spraying on a paint-like coating, helps combat this effect. 

Several scholars have argued that conditions in England in the late ninth through early eleventh centuries—namely, burgeoning literacy amid running conflicts between England’s Anglo-Saxon kingdoms and Danish invaders—were especially conducive to the production of the Old English epic poem Beowulf, and they have dated the poem’s composition accordingly. It is not inconceivable that Beowulf emerged from such a context, but privileging contextual fit over the linguistic evidence of an eighth- or even seventh-century composition requires a level of justification that thus far has not been presented.

While researching a topic, a student has taken the following notes:

• In 1971, experimental musician Pauline Oliveros created Sonic Meditations.
• Sonic Meditations is not music but rather a series of sound-based exercises called meditations.
• Each meditation consists of instructions for participants to make, imagine, listen to, or remember sounds.
• The instructions for Meditation V state, “walk so silently that the bottoms of your feet become ears.”
• Those for Meditation XVIII state, “listen to a sound until you no longer recognize it.”

While researching a topic, a student has taken the following notes:

• The Million Song Dataset (MSD) includes main audio features and descriptive tags for popular songs.
• Audio features include acoustic traits such as loudness and pitch intervals.
• Many algorithms use these audio features to predict a new song’s popularity.
• These algorithms may fail to accurately identify main audio features of a song with varying acoustic traits.
• Algorithms based on descriptive tags that describe fixed traits such as genre are more reliable predictors of song popularity.

Violins made by Antonio Stradivari and other craftspeople in the sixteenth to eighteenth centuries in Cremona, Italy, produce a sound that is considered superior to that of modern stringed instruments. Some experts have claimed that the type of wood used to create Cremonese violins is responsible for their prized sound, but modern and Cremonese violins are made of the same kinds of wood: maple and spruce. New analysis, however, has revealed unique indications that the wood in the older violins was chemically treated by the makers, leading researchers to suggest that ______blank

Generations of mystery and horror ______blank have been influenced by the dark, gothic stories of celebrated American author Edgar Allan Poe (1809–1849).

While researching a topic, a student has taken the following notes: 

• In 2013, paleontology professor Hesham Sallam and his students from Mansoura University in Egypt made a discovery.
• The team found a partial dinosaur skeleton at a site in Egypt’s Dakhla Oasis.
• The skeleton belonged to a dinosaur species that lived approximately 80 million years ago.
• The new species was named Mansourasaurus to recognize the team that discovered it.

Text 1

The Cretaceous-Paleogene (K-Pg) mass extinction event is usually attributed solely to an asteroid impact near Chicxulub, Mexico. Some scientists argue that volcanic activity was the true cause, as the K-Pg event occurred relatively early in a long period of eruption of the Deccan Traps range that initially produced huge amounts of climate-altering gases. These dissenters note that other mass extinctions have coincided with large volcanic eruptions, while only the K-Pg event lines up with an asteroid strike.

Text 2

In a 2020 study, Pincelli Hull and her colleagues analyzed ocean core samples and modeled climate changes around the K-Pg event. The team concluded that Deccan Traps gases did affect global conditions prior to the event, but that the climate returned to normal well before the extinctions began—extinctions that instead closely align with the Chicxulub impact.

In studying the use of external stimuli to reduce the itching sensation caused by an allergic histamine response, Louise Ward and colleagues found that while harmless applications of vibration or warming can provide a temporary distraction, such ______blank stimuli actually offer less relief than a stimulus that seems less benign, like a mild electric shock.

While researching a topic, a student has taken the following notes:

• The Heartbeat of Wounded Knee: Native America from 1890 to the Present is a history book by Ojibwe author David Treuer.
• In a review, a critic for The Economist noted that “Treuer’s storytelling skills shine” and that the book is an “elegant handling of [a] complex narrative.”
• A critic for O, The Oprah Magazine called it “a marvel of research and storytelling.”
• A critic for the Missoulian dubbed it “a monumental achievement.”

In Nature Poem (2017), Kumeyaay poet Tommy Pico portrays his ______blank the natural world by honoring the centrality of nature within his tribe’s traditional beliefs while simultaneously expressing his distaste for being in wilderness settings himself.

Many archaeologists assume that large-scale engineering projects in ancient societies required an elite class to plan and direct the necessary labor. However, recent discoveries, such as the excavation of an ancient canal near the Gulf Coast of Alabama, have complicated this picture. Using radiocarbon dating, a team of researchers concluded that the 1.39-kilometer-long canal was most likely constructed between 576 and 650 CE by an Indigenous society that was relatively free of social classes.

Human-made (synthetic) fibers used in clothes and many other consumer products are more durable than most natural plant ______blank the manufacture of synthetic fibers requires toxic chemical solvents that can pollute air and water.