Fourth-grade science: It's when you start to get a sense of not only how the world works, but also of why your parents used to get so nervous when, a few years before that, you would insist on asking things like, "Why is the sky blue?" and then if they could answer, follow up with, "But why does light act like that when it hits the atmosphere?" It's a matter of starting to see that first, the world is incredibly complex, second, that it takes a specialist to really understand it in detail, and most of all, it's your first glimpse of how the underlying principles that make all of existence work are actually universal, elegant and at least a little bit comprehensible to the human mind.
From the fractional distillation of crude oil to the photosynthesis taking place in all plants to the first encounter with a hypotenuse, Fibonacci, and sublimation, fourth-grade science opens up a whole lot of possibilities. Well taught, it can funnel a smart kid into the world of STEM studying and a fulfilling career, while inculcating those less scientifically minded children with a sense of wonder and curiosity. Poorly taught, of course, it can take a potential lifelong interest in science and strangle it stone dead. Let's see which of these your teacher did!
Evolution is one of the most important scientific processes to understand, as it is the one that helps one species become another. Natural selection means that random mutations result in members of a species more or less able to adapt to their environment, thrive and reproduce. Over thousands and millions of years, new species emerge.
In layman's terms, a theory is basically a guess. In science, a theory is what you have after you've proven all your guesses with stacks and stacks of evidence. Two very important theories that kids learn are the Theory of Evolution and the Theory of Gravity.
This one is important for kids to learn around 4th grade, as half of them will likely experience it in the next 2-10 years - and the other half need to understand how it all works considerably better than their predecessors did!
Mitosis is one of the main ways that cells reproduce. After mitosis, there will be two daughter cells which each have the same amount of chromosomes as the original.
The hypotenuse is the long side of a right triangle and its square is equal in size to the sum of the squares of the other two sides.
Fibonacci's sequence is found by adding together the latest two terms to get the next one. So you start with 1, then 1, then add them to get 2, then add 2+1 to get 3, and so on, resulting in 1, 1, 2, 3, 5, 8, 13, 21, 34, etc.
A conductor is a substance that a current can flow through upon the addition of voltage.
The Bernoulli Effect teaches us that when a wing is the right shape (an aerofoil shape), air will flow slightly slower OVER it than UNDER it. That means there is a little more air under the wing than above it, resulting in the air pressure above the wring being lower. This causes the wing to rise into the lower pressure area, resulting in lift and thus flight. Airplane wings, seen in cross-section, are the right shape and angle to maximize this effect.
A phylum is a grouping of living things - animals, fungi, or plants - according to their "taxonomic classification". For example, insects and arachnids are not the same CLASS of creature, but both belong to the same PHLYUM, which is arthropods.
Flowers have male and female parts. The stamen is the male part that helps it fertilize in order to reproduce.
Centripetal force is the key one here, because the bucket and water are being pulled by a string toward the middle, resulting in circular motion. Centrifugal force is the force that pulls AWAY from the center, for example when you go around a corner too fast.
Pythagoras discovered the truth about the square of the hypotenuse being equal to the sum of the squares of the other two sides of a right triangle. It may not seem very interesting, but it's very key to an awful lot of science that builds on it.
The Doppler Effect or Doppler Shift is why things sound different - not just louder, but also different - as they move toward you and away. It's a result of how the sound waves reach you faster or slower depending on where you are relative to the object and thus sound higher or lower than they really are.
As Alexander Pope said, "Fools rush in where angels fear to tread" or W. B. Yeats framed it, "The best lack all conviction, while the worst are full of passionate intensity." Dunning Kruger is a theory (remember, theory in the scientific sense, as in something with a mountain of evidence) that smart people doubt themselves because they know what they don't know, while dumb people just assume they're right and sound really confident.
Since energy is never created or destroyed, merely converted (thank you, Einstein!), that means an object which moves and then stops must still have that kinetic energy somewhere. If it didn't come off as thermal energy, then it's still there and could be unleashed, ready to go again. Think of a ball ready to drop 10 feet: you know if you let go, it'll move! That's potential energy.
"Omni" comes from the Greek word for everything and as such, an omnivore is one who eats everything.
Deciduous trees drop their leaves in the autumn and make new ones in the spring. An evergreen tree does not.
Isosceles triangles can be effectively folded in half along the center line to get two right triangles.
Erosion is what makes rivers slowly move, coastlines change and rock formations, well, form.
Migrating animals include certain birds and herds which move throughout the year to follow the available good weather and grazing or foraging opportunities. Some types of birds summer in the UK but winter in Africa, meaning their annual trip is about 10,000 miles!
"Mrs. Gren" is how you remember the seven processes that all living things enjoy: movement, respiration, sensitivity, growth, reproduction, excretion and nutrition. All living things do these, though not always the same way.
When a thing is translucent, it means the light can go through but that it will be redirected (that is, scattered) when it does. For example, a sheet of glass is transparent, but a sheet of gauze is translucent.
Phosphoresence used to be considered very magical because emitting light without combustion or heat means using energy in a very special way. Natural examples of phosphorescence include many glowing sea creatures and also the Northern Lights.
An ecosystem is a localized or planet-wide phenomenon. It takes the concept of, for example, the food chain and expands on it to create a food web, and then includes environmental factors.
When a seed is ready to start becoming a plant, it will germinate a sprout. This is the beginning of the new plant.
A barometer measures air pressure. These days we find it a bit weird that ordinary people used to have these on the wall all the time often as large as their clock, but actually in the days before accurate weather forecasts thanks to our modern technology, a barometer was a marvelous way to know what weather was probably coming in later that day.
A contour line is on land and is a great way to show height above sea level, or altitude. If the lines are closer together it means the land is steeper. Most humans seem to instinctively be able to read contour lines.
A hypothesis is a very educated guess. Scientists come up with one before doing an experiment to either prove or disprove it. For example, if you hypothesize that if you drop something, it will fall, then drop a bunch of things and they all fall, you have tested your hypothesis and proven it was correct.
The Greenhouse Effect is the way that additional water vapor or heat-trapping gases (e.g. carbon dioxide or methane) hold more warmth in the air, thus warming the planet, contributing to global warming which is one of the main elements of climate change. Other elements of climate change include sea level rise, drought, and ice caps melting.
Earth's surface is covered in "plates" of land that float very very slowly on a subterranean ocean of magma. These plates rub against each other, go under and over each other, and sometimes cause earthquakes and volcanoes. This process is called tectonics.
Distillation, in science, means when you take a thing that is all mixed up - eg crude oil - and apply a process to it to break it back down into its components. Eg the fractional distillation of crude oil, which is not very useful as is, results in many useful things: gasoline, petroleum, naphtha, kerosine, diesel, fuel oil, lubricant oil and bitumen.
Visible light is made up of lots of colors that all have slightly different wavelengths, meaning they interact with different substances differently. When light hits a new substance at the right angle - eg when it goes from the air into a diamond - it splits into these component colors, resulting in a rainbow. This is called diffraction.
Thanks to photosynthesis, plants use the sun's light (ie the "photo" part) to eat up carbon dioxide and make (the "synthesis" part) food and oxygen, meaning they grow faster when CO2 levels rise or you water them. Still, even a plant can have too much of a good thing, meaning carbon dioxide, sunlight and water levels should be within certain parameters.
A cell is the smallest building block of a organism, which is any living thing. Animal cells usually have a soft membrane while plant ones tend to have a more rigid membrane called cellulose.
Quarks have never been seen, but we know they must exist because they explain the behavior of all matter. They are the building blocks of atoms, which are the building blocks of everything else.