Stars & Sky
Why does the Sun appear brighter than other stars in our sky?
The Sun appears brighter because it is closest star to Earth. Even though other stars may be larger, distance makes them appear much dimmer.
What is matter made of?
Matter is made of tiny particles called atoms that join together to form molecules. These particles are too small to see with our eyes.
Where is most of Earth's freshwater located?
Most of Earth's freshwater is frozen in glaciers and polar ice caps, or stored underground as groundwater. Only a tiny fracvtion is in lakes, rivers, and the atmosphere.
What is a food web?
A food web is a diagram that shows what eats what in an ecosystem.
Name the three states of matter and give an example of water in each state.
Solid - Ice, Liquid - Water, Gas - Water Vapor
What causes day and night?
Earth's spin (rotation) causes day and night. When your location faces the Sun, it is daytime. When your location faces away the Sun, it is nightime.
What happens when you dissolve sugar in water?
When sugar dissolves in water, it is a physical change. The sugar molecules spread apart and mix evenly with the water molecules, but the sugar molecules don't change into different molecules.
What is condensation?
Condensation is when water vapor cools down and turns into liquid water. This happens when water vapor in the air moves higher into the atmosphere where it is colder.
Where does all the energy in an ecosystem originally come from?
All energy in an ecosystem comes from the Sun. Plants capture energy from sunlight to make food, and animals get energy by eating plants or other animals.
What is a model in Science and why do scientists use them?
A model is something scientists make to represent the real world and answer questions about things they cannot see or observe directly.
What is the difference between Earth's rotation and Earth's orbit?
Earth's rotation is when Earth spins on its axis. Earth's orbit is when Earth moves around the Sun.
What is chromatography and what does it show?
Chromatography is a technique that separates mixtures into their individual substances. It shows that different dyes have different properties, which is why they separate at different heights on the paper.
Explain the rain-shadow effect.
The rain shadow effect occurs when wind blows moist air toward a mountain. The air rises and cools, causing water vapor to condense and fall as rain on the windward side. The air descends on the leeward side, becoming dry, so little rain falls there.
What do decomposers do in an ecosystem?
Decomposers (like bacteria, fungi, and earthworms) break down dead plant and animal matter.
Explain the relationship between atoms and molecules
As Earth orbits the Sun, it is in different positions around the Sun at different times of year. When Earth faces away from the Sun at different times of year, it faces different directions in space, so we see different constellations.
What is an emulsifier and why is it important?
An emulsifier is a substance that allows two liquids that normally don't mix (like oil and vinegar) to stay mixed together. The emulsifier molecules attract to both types of liquid molecules, holding them together.
How do the four spheres of Earth interact to create rain?
The hydrosphere (water) evaporates into the atmosphere (air). Wind in the atmosphere moves this water vapor toward mountains (the geosphere). As air rises over the mountain and cools, water vapor condenses and falls as rain. Life forms in the biosphere.
Explain why plants get most of their matter from air and water, not soil.
Plants use water molecules from soil, carbon dioxide molecules from the air, and energy from the Sun to make food through photosynthesis. Soil provides nutrients.
How are physical changes and chemical changes different?
In a physical change, matter changes form but the molecules stay the same. In a chemical change, substances combine and new substances with different properties form.
How does gravity affect people living in different locations on Earth?
Earth's gravity pulls all objects toward Earth's center. No matter where you live on Earth, gravity pulls you down toward the ground, even though Earth is a sphere and down points in different directions around the planet.
State the Law of Conservation of Mass and give an example.
The Law of Conservation of Mass states that matter is never created or destroyed - it only changes form.
How can wastewater treatment help solve a water shortage?
Wastewater treatment uses chemical reactions to remove harmful substances from used water, making it clean and safe to reuse. By treating and reusing wastewater, communities can have more freshwater available for their needs.
How can a newly introduced species damage an ecosystem?
A newly introduced species can damage an ecosystem by competing for resources, eating organisms that have no natural predators to control them, or disrupting the food web balance.
Describe how matter and energy flow through an ecosystem, starting with the Sun.
The Sun provides energy to plants, which use it make food from air and water.