Why do we have the illusion that cramming for an exam is the best learning strategy? Because we are unable to differentiate between the various sections of our memory. Immediately after reading our textbook or our class notes, information is fully present in our mind. It sits in our conscious working memory, in an active form. We feel as if we know it, because it is present in our short-term storage space ... but this short-term section has nothing to do with the long-term memory that we will need in order to recall the same information a few days later. After a few seconds or minutes, working memory already starts disappearing, and after a few days, the effect becomes enormous: unless you retest your knowledge, memory vanishes. To get information into long-term memory, it is essential to study the material, then test yourself, rather than spend all your time studying.

The discovery of mirror neurons has profoundly changed the way we think of a fundamental human capacity, learning by observation. As children we learn a lot by observing what our parents and friends do. Newborns, in the first week of life, have an inborn tendency to stick out their tongue if their parents stick out theirs. Such imitation is not perfect. You may not see the tongue stick out each time you stick yours out at your newborn, but if you do it many times, the tongue will come out more often than if you do something different. Babies babble and later start to imitate the sounds their parents produce. Later still, they play with vacuum cleaners and hammers in imitation of their parents. Our modern cultures, in which we write, speak, read, build spaceships and go to school, can work only because we are not restricted to the behavior we are born with or learn by trial and error. We can learn a lot by simply watching others.

Have you ever been surprised to hear a recording of your own voice? You might have thought, "Is that really what my voice sounds like?" Maybe your accent is more pronounced in the recording than you realized, or your voice is higher than it seems to your own ears. This is of course quite a common experience. The explanation is actually fairly simple. There are two pathways through which we perceive our own voice when we speak. One is the route through which we perceive most external sounds, like waves that travel from the air through the outer, middle and inner ear. But because our vocal cords vibrate when we speak, there is a second internal path. Vibrations are conducted through our bones and stimulate our inner ears directly. Lower frequencies are emphasized along this pathway. That makes your voice sound deeper and richer to yourself than it may sound to other people.

Biologists distinguish two kinds of similarity. "Analogous" traits are ones that have a common function but arose on different branches of the evolutionary tree and are in an important sense not "the same" organ. The wings of birds and the wings of bees are both used for flight and are similar in some ways because anything used for flight has to be built in those ways, but they arose independently in evolution and have nothing in common beyond their use in flight. "Homologous" traits, in contrast, may or may not have a common function, but they descended from a common ancestor and hence have some common structure that indicates their being "the same" organ. The wing of a bat and the front leg of a horse have very different functions, but they are all modifications of the forelimb of the ancestor of all mammals. As a result, they share nonfunctional traits like the number of bones and the ways they are connected. To distinguish analogy from homology, biologists usually look at the overall architecture of the organs and focus on their most useless properties.

Seawater contains an abundance of dissolved oxygen that all marine animals breathe to stay alive. It has long been established in physics that cold water holds more dissolved oxygen than warm water does ― this is one reason that cold polar seas are full of life while tropical oceans are blue, clear, and relatively poorly populated with living creatures. Thus, as global warming raises the temperature of marine waters, it is self-evident that the amount of dissolved oxygen will decrease. This is a worrisome and potentially disastrous consequence if allowed to continue to an ecosystem-threatening level. Now scientists have analyzed data indicating that the amount of dissolved oxygen in the oceans has been declining for more than a half century. The data show that the ocean oxygen level has been falling more rapidly than the corresponding rise in water temperature. Falling oxygen levels in water have the potential to impact the habitat of marine organisms worldwide and in recent years this has led to more frequent anoxic events that killed or displaced populations of fish, crabs, and many other organisms.

Capuchins ― New World Monkeys that live in large social groups ― will, in captivity, trade with people all day long, especially if food is involved. I give you this rock and you give me a treat to eat. If you put two monkeys in cages next to each other, and offer them both slices of cucumber for the rocks they already have, they will happily eat the cucumbers. If, however, you give one monkey grapes instead ― grapes being universally preferred to cucumbers ― the monkey that is still receiving cucumbers will begin to throw them back at the experimenter. Even though she is still getting "paid" the same amount for her effort of sourcing rocks, and so her particular situation has not changed, the comparison to another makes the situation unfair. Furthermore, she is now willing to abandon all gains ― the cucumbers themselves ― to communicate her displeasure to the experimenter.

Higher education has grown from an elite to a mass system across the world. In Europe and the USA, increased rates of participation occurred in the decades after the Second World War. Between 2000 and 2014, rates of participation in higher education almost doubled from 19% to 34% across the world among the members of the population in the school-leaving age category (typically 18-23). The dramatic expansion of higher education has been marked by a wider range of institutions of higher learning and a more diverse demographic of students. Changes from an elite system to a mass higher education system are associated with political needs to build a specialised workforce for the economy. In theory, the expansion of higher education to develop a highly skilled workforce should diminish the role of examinations in the selection and control of students, initiating approaches to assessment which enable lifelong learning: assessment for learning and a focus on feedback for development. In reality, socio-political changes to expand higher education have set up a ‘field of contradictions' for assessment in higher education. Mass higher education requires efficient approaches to assessment, such as examinations and multiple-choice quizzes, with minimalist, impersonal, or standardised feedback, often causing students to focus more on grades than feedback. In contrast, the relatively small numbers of students in elite systems in the past allowed for closer relationships between students and their teachers, with formative feedback shaping the minds, academic skills, and even the characters of students.