LITERARY NARRATIVE: This passage is adapted from the book Braiding Sweetgrass: Indigenous Wisdom, Scientific Knowledge, and the Teachings of Plants by Robin Wall Kimmerer (©2013 by Robin Wall Kimmerer).

Even now, after more than fifty Strawberry Moons, finding a patch of wild strawberries still touches me with a sensation of surprise, a feeling of unworthiness and gratitude for the generosity and kindness that comes with an unexpected gift all wrapped in red and green. "Really? For me? Oh, you shouldn't have." After fifty years they still raise the question of how to respond to their generosity: Sometimes it feels like a silly question with a very simple answer: eat them.

[2] But I know that someone else has wondered these same things. In our Creation stories the origin of strawberries is important. Skywoman's beautiful daughter, whom she carried in her womb from Skyworld, grew on the good green earth, loving and loved by all the other beings.  But tragedy befell her when she died giving birth to her twins, Flint and Sapling. Heartbroken, Sky woman buried her beloved daughter in the earth. Her final gifts, our most revered plants, grew from her body. The strawberry arose from her heart. In Potawatomi, the strawberry is ode min, the heart berry. We recognize them as the leaders of the berries, the first to bear fruit.

Strawberries first shaped my view of a world full of gifts simply scattered at your feet. A gift comes to you through no action of your own, free, having moved toward you without your beckoning. It is not a reward; you cannot earn it, or call it to you, or even deserve it. And yet it appears. Your only role is to be open-eyed and present. Gifts exist in a realm of humility and mystery-as with random acts of kindness, we do not know their source.

Those fields of my childhood showered us with strawberries, raspberries, blackberries, hickory nuts in the fall, bouquets of wildflowers brought to my mom, and family walks on Sunday afternoon. They were our playground, retreat, wildlife sanctuary, and ecology classroom. All for free. Or so I thought.

I experienced the world in that time as a gift economy, "goods and services" not purchased but received as gifts from the earth.  Of course I was blissfully unaware of how my parents must have struggled to make ends meet in the wage economy raging far from this field.

In our family, the presents we gave one another were almost always homemade. I thought that was the definition of a gift: something you made for someone else. We made all our Christmas gifts: piggy banks from old bottles of bleach, hot pads from broken clothespins, and puppets from retired socks. My mother says it was because we had no money for store-bought presents. It didn't seem like a hardship to me; it was something special.

My father loves wild strawberries, so for Father's Day my mother would almost always make him strawberry shortcake. She baked the crusty shortcakes and whipped the heavy cream, but we kids were responsible for the berries. We each got an old jar or two and spent the Saturday before the celebration out in the fields, taking forever to fill them as more and more berries ended up in our mouths. Finally, we returned home and poured them out on the kitchen table to sort out the bugs. I'm sure we missed some, but Dad never mentioned the extra protein.

In fact, he thought wild strawberry shortcake was the best possible present, or so he had us convinced. It was a gift that could never be bought.  As children raised by strawberries, we were probably unaware that the gift of berries was from the fields themselves, not from us. Our gift was time and attention and care and red-stained fingers. Heart berries, indeed.

Gifts from the earth or from each other establish a particular relationship, an obligation of sorts to give, to receive, and to reciprocate. The field gave to us, we gave to my dad, and we tried to give back to the strawberries. When the berry season was done, the plants would send out slender red runners to make new plants. Because I was fascinated by the way they would travel over the ground looking for a good place to take root, I would weed out little patches of bare ground where the runners touched down. Sure enough, tiny little roots would emerge from the runner and by the end of the season there were even more plants, ready to bloom under the next Strawberry Moon. No person taught us this-the strawberries showed us. Because they had given us a gift, an ongoing relationship opened between us. .

Farmers around us grew a lot of strawberries and frequently hired kids to pick for them. My siblings and I would ride our bikes a long way to Crandall's farm to pick berries to earn spending money. A dime for every quart we picked.

SOCIAL SCIENCE: This passage is adapted from The Air plane: How Ideas Gave Us Wings by Jay Spenser (©2008 by Jay Spenser).

The invention of the airplane was a battleground for two warring paradigms about what the airplane would be like. Paradigms are mind-sets created by what we think we know. Depending on how closely they match the actuality, these mental models either can help us succeed or can place blinders over our eyes that keep us from perceiving  what we later realize was obvious all along. ·

Working under the right paradigm helped Americans Orville and Wilbur Wright to succeed even as a wrong one sabotaged the hopes of Europe's many experimenters. If not for this situation, the French who felt they had invented flight because of the success of the Montgolfiers’ hot-air balloons in 1783-might well have been first. If so, the airplane, like the automobile before it, would have been a European invention.

What led Europe's aerial experimenters astray? It was William Samuel Henson . Or more accurately, it was the powerful sway of Henson's persuasive vision of what aviation would be.

First published in the early 1840s, the engraved · illustrations   of   the Henson   Aerial Steam   Carriage (a passenger-carrying airplane) continued to appear off and on in newspapers, magazines, and books for more than a half century. More thrilling artwork of heavier than -air flying machines was hard to imagine, and the very sight of this aerial stagecoach spurred Europe's aerial experimenters to redouble their efforts. Unfortunately, however, it also handed them a lot of incorrect notions.

The concept of an aerial carriage brought with it a concomitant expectation that people would drive airplanes around the sky making flat turns as they did in horse-drawn vehicles. This unquestioned assumption shaped how France's early experimentation approached airplane design, and it cost them dearly.

Part of Henson's paradigm worked. For example, airplanes would indeed pitch their noses up or down to climb or descend. This was intuitive because horse drawn carriages do just that when traversing hilly countryside. But carriages don't tilt sideways, or at least not very far, because that leads to a catastrophic upset.

Henson's vision told Europe's early experimenters that their airplanes must not be permitted to tilt side to side or else catastrophe would ensue. To ensure that this never happened, some experimenters used strongly upward-angled wings so that the airplane would be self- righting in flight. Others placed vertical fore-and-aft fabric panels between the wings of their biplanes to prevent side slips. Both these features suggest that Europe's pioneers were terrified of banking, or dropping a wing in flight.

Another place where Henson's Aerial Steam Carriage paradigm misled people was the vital issue of controllability. Controlling horse-drawn vehicles does not require constant active involvement on the driver's part. The horses are set in motion and the reins are not used again until the horses need further instruction.

Consequently, Europe’s “early birds" were remarkably cavalier about controllability. To them, all one needed to do was create an inherently stable craft whose wings never dropped to either side. After nosing this vehicle aloft, one would simply "drive" it around the sky.

A wealthy Brazilian named Alberto Santos- Dumont performed Europe's first heavier-than-air flights late in 1906. His 14-bis was largely uncontrollable, but that didn't bother him; his goal was simply to get into the air. This disregard for a key requirement of flight was then so pervasive that more than a year would pass before any European figured out how to actually land where he had taken off.

Wilbur and Orville worked under a different mind set. They too had seen Henson's artwork, but it didn't sing to them because they were bicyclists. Their intimate association with this vehicle, its operation, and its manufacture led them to approach flight development in a different way than their European counterparts.

Wilbur and Orville were not in the least scared of tilting to one side or the other in flight. Banking in flight seemed natural to them because a bicyclist leans into turns. What's more, they understood from the outset that the airplane needed to be controllable around all three axes and that the pilot had to be intimately involved with this process while aloft. These two insights were intuitive because the bicyclist must constantly direct his two-wheeled vehicle by means of a combination of active balance and coordinated use of handlebars, acceleration, and braking. If the bicyclist doesn't stay on top of these things every minute, he's in for a spill.

HUMANITIES: Passage A is adapted from the biography Duke: A Life of Duke Ellington by Terry Teachout (©2013 by Terry Teachout). Passage B is adapted from the biography I'll Take You There: Mavis Staples, The Staples Singers, and the March up Freedom's Highway by Greg Kot (©2014 by Greg Kot).

Passage A by Terry Teachout

What Duke Ellington sought and got from his "accumulation of personalities" was a loose, festive ensemble sound far removed from the clean precision of Benny Goodman's band. He had no interest in the smoothly blended playing that leaders like Goodman, Jimmie Lunceford, and Artie Shaw demanded from their groups. He preferred to hire musicians with home made techniques that were different to the point of apparent incompatibility, then juxtapose their idiosyncratic sounds as a pointillist painter ·might place dots of red and green side by side on his canvas, finding inspiration in their technical limitations ("With a musician who plays the full compass of his instrument as fast or as slow as possible, there seems, paradoxically, less opportunity to create"). That is why his charts never so1,1nd quite right when performed by other groups, however accomplished the individual players may be. It is also why a keen-eared virtuoso like Jack Teagarden, the greatest jazz trombonist of his generation, found it impossible to enjoy the Ellington band. "I never did anything like Ellington ever did," he said. "He never had a band all in tune, always had a bad tone quality and bad blend." What Teagarden meant, whether he knew it or not, was that the band had an unconventional tone quality, one that had little in common with received ideas about how a big band ought to sound. Asked why he hired Al Hibbler when he already had a singer on the payroll, Ellington replied, "My ear makes my decision." To him, no other ear mattered.

[2] Billy Strayhorn, who saw Ellington's working methods up close and understood them best, gave them a name in a 1952 article about his mentor: "Ellington plays the piano, but his real instrument  is the band. Each member of his band is to him a distinctive tone color and set of emotions, which he mixes with others equally distinctive to produce a third thing, which I call the Ellington Effect." Sometimes he worked "on" his players as a choreographer makes a ballet "on" his dancers, passing out or dictating scraps of music, then shaping and reshaping them on the spot into a piece that would later be reduced to written form. Even a work that had already been notated was subject in the heat of the moment to total transformation motivated solely by the whim of the composer. The goal, he explained, was “to mold the music around the man," and the men around whom his music was so tightly molded rarely sounded more themselves than when they were playing it.

Passage B by Greg Kot

In a six-member male gospel group calling themselves the Trumpet Jubilees, Pops was third lead, singing mostly in a falsetto voice, and managed the group, booking their appearances and scheduling the rehearsals. He was a stickler for punctuality and precision, for looking and sounding sharp, for taking the job seriously. But not everyone in the group shared his commitment; his exasperation mounted until one day he quit. Pops decided to devote his time to a singing group that he could run from top to bottom that would show up on time at every rehearsal with no questions asked. Mostly, he wanted to sing because it was a crucial part of his identity; since boyhood all he could remember was the pleasure singing brought him and his older brothers and sisters. When singing in the Trumpet Jubilees became a chore, he turned to his family.

"One night he came home early because the guys in the Trumpet Jubilees didn't show up for rehearsal," Mavis says. "He was disgusted. He went into the closet in the living room and got a little guitar he had brought home from the pawnshop. It didn't have more than three or four strings on it, but it was enough to get us started."

Mavis, Pervls, Cleotha, and Yvonne sat in a semi circle in front of their father on the beige carpet in their living room at 506 East 33rd Street. Pops hunched over his $7 guitar and plucked a series of notes, assigning one to each of his children.

"People always ask, 'How do we get the sound we have?' And that came from my father-the sound he had with his family in Mississippi when they sang in the gallery after dinner. He gave us [an E chord] and the parts his brothers and sisters would sing. He would hit a note on his guitar and would say, 'Now, Mavis go here,' a baritone part, because even then I had the deepest voice. Pervis was second lead behind Pops because he had the most experience, and he could hit those high notes like Michael Jackson later could. Cleedi had high harmony. The first song he taught us was 'Will the Circle Be Unbroken."'

NATURAL SCIENCE: This passage is adapted from the article "Tales from the Pit" by Andrew Curry (©2014 by Smithsonian Institution).

The Messel Pit, located in central Germany, is known for its fossils of mammals from the Eocene epoch. 

At some point around 50 million years ago, underground water came into contact with a vein of molten · rock. High-pressure steam erupted, forming a crater with steep sides. As water seeped in, it created a lake shaped more like a drinking glass than a soup bowl. Any animal that fell in sank quickly to the bottom.

Still, that alone doesn't explain why so many land mammals-not to mention birds, bats and insects-perished in the lake that became the Messel Pit.  One theory is that carbon dioxide periodically bubbled up from deep beneath the lake bottom, smothering animals near the shore. Another possibility is that some of the summer algae blooms were toxic, poisoning animals that had chosen the wrong time and place to slake their thirst. Or perhaps smaller animals died nearby and were washed in by small floods or rushing streams. 

The lake was so deep that oxygen didn't circulate near the bottom, which meant that there were no bottom feeders around to consume the dead and dying animals. Year after year, algae scrumming the lake surface bloomed and died, and so layers of fine clay and dead microorganisms drifted to the bottom. Each layer was as thick as a strand of hair. It took 250 years to build up an inch of mud. Over millions and millions of years, plants and animals were preserved like flowers pressed between the pages of a book, and the algae and other organic matter turned into oil shale.

[2] Among the thousands of fossils that paleontologists have recovered at Messel Pit are specimens representing nearly 45 different mammal species. Those finds are critical to understanding how warm-blooded creatures evolved. Mammals and dinosaurs appeared at nearly the same time around 200 million years ago. But dinosaurs were so well suited to the environment that they crowded out any competition. Mammals lived on the margins, mostly tiny creatures eking out a living by eating insects under the cover of darkness. "They just tried to stay out of the way," says Thomas Lehmann, a Senckenberg Research Institute paleontologist. And so it went for nearly 150 million years.

Then, in an instant, everything changed, apparently when an asteroid or comet struck Earth 66 million years ago and dramatically altered the climate, eventually wiping out the giant reptiles.  The diversity of species found among the Messel Pit fossils reveals that mammals rushed to fill every empty ecological nook and cranny they could find. "They really tried everything-flying, jumping, running, tree-dwelling, ant eating," says Lehmann. "From the point of view of evolution, Messel is a fantastic laboratory to see what life might have given us."

Might have, but in many cases didn't. Messel's most fascinating specimens may be those species that have no living relatives, though they look jarringly familiar. In the visitor center, kids crowd around to watch as a conservator aimed with toothbrushes, dental picks and scalpels cleans layers of oil shale away from a fossil unearthed just a few weeks earlier. To me, the skeleton of Ailuravus macrurus looks like that of a giant squirrel. It's three feet long, including its bushy tail. Near the ribs a black stain traces the creature's fossilized digestive tract. Despite its tail, Ailuravus is no squirrel ancestor. It's an evolutionary dead end; Ailuravus and all of its relatives died out more than 37 million years ago. Why? Maybe they fell victim to climate changes, or a better-adapted competitor, or disappearing food sources, or simple bad luck.

Ailuravus' resemblance to a modern squirrel is an example of evolutionary convergence. Given enough time, adaptations may lead to nearly identical ·solutions-bushy tails, say, or powerful, kangaroo-like hind legs-popping up in different species. "It's like using the same interlocking toy bricks to build different forms," says Lehmann   .

And there are forms aplenty at the Messel Pit. The exquisitely preserved fossils have provided paleontologists with unprecedented insights into the adaptive strategies-some successful, others not-adopted by mammals for feeding, movement and even reproduction. For instance, the contents of the tiny prehistoric horse’s stomach-fossilized leaves and grape seeds indicate that the animal was not a grazer but a browser, eating what it found on the forest floor. The paleontologists also found eight fossilized specimens of pregnant mares, each carrying a single foal. That discovery suggests that the early horses had already adopted herd behavior, since joint care would be the best way to guarantee the survival of small numbers of offspring.