Science 6

The particle model states that heating matter causes its particles to move faster: the particles in a pot of water move faster and faster as the stove warms it.

Particles are always moving, even in cold matter.

Expansion is the typical response of materials to heating and contraction the typical response to cooling: a tight metal jar lid loosens under hot water because it expands, and a balloon shrinks in a freezer.

Heat makes the particles move faster and spread apart, so the material takes up more space; cooling does the reverse.

As particles move faster, the attractive forces between them weaken and the space between them increases, which is why heated matter expands.

Faster particles push one another farther apart and the pull between them holds them less tightly.

Most matter expands when heated and contracts when cooled, but by different amounts: gases expand the most, liquids less, and solids the least.

A gas's particles are already far apart and barely held together, so heating spreads them much farther.

Cooling matter causes its particles to move slower, so the attractive forces between them increase and the space between them decreases: a juice can in a fridge cools as heat leaves it and its particles slow down.

There is no substance called cold that flows into things.

External forces act on an object from outside it: a hand pushing a box, the ground rubbing against a sliding sled, and a stretched trampoline pushing up on a jumper are all external forces.

To find the external forces on something, look at everything touching it from outside, and add gravity, which pulls on it without touching.

Some energy resources can be used before processing, as they come from nature: wood burned in a campfire, wind filling a sailboat's sail, and moving water turning a water wheel.

Using a resource before processing means using it directly, without changing it into another form first.

Responsible management of energy resources begins with minimal disruption to nature: placing well sites, roads and pipelines to avoid wetlands and wildlife routes, and drilling several wells from one pad.

Each road and clearing cuts into habitat, so careful planning keeps the footprint small.

An applied force is exerted on an object by a person or another object: a soccer player's kick, a wagon pulled by its handle, and a snowplow's blade pushing snow are applied forces.

Applied forces are the pushes and pulls you can see someone or something giving.

Other energy resources are used after processing, changed into a more useful form first: crude oil is refined into gasoline, uranium is made into nuclear fuel, canola or grain is made into biofuel, and wind, sunlight and moving water are turned into electricity.

Processing makes an energy resource easier to store, move or use.

Earth's systems, the atmosphere, hydrosphere, lithosphere and biosphere, interact with the Sun and with each other to shape climate, the usual weather of a place over 30 years or more.

The Sun supplies the energy, and Earth's systems decide what happens to it: clouds and ice send some back to space, oceans store heat and carry it around the globe, and gases in the air hold some in.

Climate change can affect land, plants, humans and other animals by changing weather and extreme weather events, migration patterns, water resources and how often forest fires happen.

These effects are measured in Canada, not only in faraway places: Alberta has seen fiercer fire seasons, droughts on the prairies and glaciers in the Rockies shrinking year after year.

Climate change is identified through long-term observation and measurement of weather conditions, such as precipitation, temperature and the number of extreme weather events, compared across many years.

Weather changes every day, so a single measurement says almost nothing about climate.

Clouds reflect sunlight into space: about 29% of the sunlight reaching Earth is reflected away, mostly by clouds, which is why a cloudy summer afternoon stays cooler than a clear one.

The tops of clouds are bright white, and they bounce sunlight back up before it reaches the ground; bright snow, ice and tiny particles in the air reflect some too.

Climate change can make extreme weather events stronger and more frequent: warmer air holds more water vapour, so heavy rains can be heavier, and heatwaves become hotter and more common.

A warmer atmosphere has more energy and more moisture to work with.

Ecosystems are complex systems of biotic and abiotic components: biotic components are living or once-living things, such as plants, animals, fungi and micro-organisms, and abiotic components were never alive.

A slough in Alberta holds cattails, ducks, frogs, insects and countless bacteria too small to see, all biotic, along with water, mud, air and sunlight, all abiotic.

All components of an ecosystem influence each other, either directly, like a moose eating willow, or indirectly, like sunlight warming a pond so its algae grow faster and the snails that eat them have more food.

A direct influence is one part acting on another; an indirect one passes through a third part.

Photosynthesis is the process in which plants use light, water and carbon dioxide to produce oxygen and food in the form of a sugar called glucose.

Roots take up water, leaves take in carbon dioxide from the air through tiny openings, and light supplies the energy.

Plants play a variety of roles in an ecosystem: they photosynthesize, making food and oxygen, they clean and filter water, they reduce soil erosion, and they provide food and shelter for animals.

A single willow along a creek feeds moose and beavers, shelters songbirds, shades the water for fish and holds the bank together with its roots.

Micro-organisms, living things too small to see without a microscope, such as bacteria, are biotic components of every ecosystem: a single teaspoon of healthy soil can hold hundreds of millions of bacteria.

Bacteria break down dead matter, some help plant roots take up nutrients, and some live inside animals' stomachs and help digest food.

Celestial bodies are natural bodies located beyond Earth's atmosphere, such as the Sun, the Moon, planets, asteroids and comets, so a satellite built by people is not a celestial body.

The word celestial means of the sky.

Textbook pictures of the solar system squash the distances so everything fits on a page: in reality Neptune is about 30 times farther from the Sun than Earth, and the space between the planets is almost entirely empty.

A true-scale picture of the distances would be almost blank, with the planets too small to see.

Technologies used to explore the solar system include telescopes, satellites, probes, rovers, crewed spacecraft and space stations, and computer modelling, and each gathers a different kind of knowledge.

Telescopes see far away from Earth or from orbit; satellites circle Earth or other worlds; probes fly to distant planets; rovers drive across a surface; crewed spacecraft and space stations carry people; and computer models calculate what cannot be watched directly.

The solar system is a complex group of celestial bodies: the Sun, a star, eight planets and their moons, dwarf planets, asteroids, comets and meteoroids.

8% of the solar system's mass, and everything else travels around it.

The planets are almost never lined up in a row: each orbits at its own speed, Mercury in 88 days and Neptune in about 165 years, so they are scattered around their orbits.

Diagrams show the planets in a line because it fits on a page.

An abstraction is a simplified version of something complex that keeps only what matters for a purpose: a transit map shows the stops and lines but leaves out the streets, buildings and trees.

Abstraction makes a problem easier to think about by hiding detail that does not matter right now.

Computational artifacts, things people create with computers, can be designed to address society's needs and wants, from weather modelling and communications to car controls, medical research and apps.

A need is something people must have, like safe roads or warnings about storms; a want is something people would like, like a game or a music app.

The process of abstraction includes determining what details to keep and what to ignore, and removing the unnecessary ones: a pancake recipe keeps the ingredients, amounts and steps and leaves out the colour of the bowl.

What to keep depends on the purpose: a weather app keeps the temperature and the chance of rain but ignores the exact shape of each cloud.

Weather models and communication networks are coded artifacts: computers run weather models that calculate tomorrow's weather from millions of measurements, and code routes every call, text and video across phone networks.

A forecast that warns of a blizzard two days ahead gives people time to prepare, and the same networks carry the warning to their phones.

Identifying important information means picking out what a problem depends on: to plan how many buses a field trip needs, the number of people and seats matters, while everyone's names do not.

Once the important information is found, the problem often becomes a simple calculation or a short plan.

Scientific explanations make sense of natural phenomena based on investigation: they answer scientific questions, such as why ice floats, with claims backed by what was observed and measured.

A natural phenomenon is anything that happens in nature that can be observed, from a rainbow to a puddle drying up.

First Nations, Métis and Inuit share explanations of natural phenomena through written texts, traditional knowledge, visual forms, verbal presentations, and stories and legends.

These explanations rest on generations of careful observation of the land, water, animals and sky, tested by living on the land.

A scientific explanation has three parts: a claim, what is said to be true; evidence, the observations or measurements that support it; and reasoning, why that evidence supports the claim.

For example: the claim is that seedlings grow toward light; the evidence is that seedlings on a windowsill bent toward the window within a few days; the reasoning is that the light came from one side only, so the light's direction caused the bending.

Traditional knowledge explains patterns in nature through names and teachings: Plains Cree names for the moons of the year, such as the Goose Moon in March, tie the sky's cycle to what happens on the land.

Naming each moon for what happens on the land records when geese return and when frogs begin to call, a calendar built from long observation.

Scientific explanations must be testable, or falsifiable: an investigation could support or contradict them, so 'ice floats because it is less dense than water' is scientific, while 'ice floats because it wants to' is not.

A testable explanation makes a prediction that could turn out wrong: if ice floats because it is less dense, then other things less dense than water should float too, and that can be checked.