Matter & Conservation
What do we call the tiny pieces that all matter is made of, even though you can't see them with your eyes?
Atoms or particles
Is dissolving sugar in water a physical change or a chemical change? Explain briefly.
Physical change (sugar dissolves; can be recovered by evaporation)
What kind of force pulls objects toward Earth’s center?
Gravity
What is the main source of energy for Earth systems (light and warmth)?
The Sun
Which object in our sky is the primary source of light and energy for Earth?
The Sun
In a closed system, when a substance melts or is cut into smaller pieces, what stays the same even though its shape or form changes?
Matter (or Mass)
Give one observable sign that a chemical change has happened (give a 1–3 word answer).
Color change, gas produced, temperature change, or precipitate formed
If two equal forces act on an object in opposite directions, what happens to the object’s motion?
They cancel and the object stays at constant velocity or remains at rest
When a person eats food, that chemical energy came from what original source?
The Sun (through photosynthesis in plants)
Draw or describe the direction of Earth's gravitational force on a thrown ball (toward what point?).
Toward the center of Earth
True or False: When two substances react chemically to form a new substance, the total amount (mass) of matter can disappear.
False — mass is conserved
Describe a simple investigation (materials and one step) to test whether a mixture creates a new substance or only a physical mixture.
Mix baking soda and vinegar in a sealed bag and measure mass before and after (chemical) OR mix sand and salt and filter to recover (physical)
Name one example of a noncontact force (an object affects another without touching).
Gravity, magnetism, or static electricity
Provide one example of energy transfer when a moving object hits another object.
A moving billiard ball hits another ball and transfers kinetic energy
Explain why we see different phases of the Moon (one sentence).
We see different parts of the Moon’s sunlit side as it orbits Earth
A sealed jar contains a chemical reaction. Name one type of data you could collect to show the amount of matter is conserved.
Mass measurements before and after (balance), gas collected, or particle count estimates
Four samples:
iron filings + sulfur (mixed)
baking soda + vinegar (react)
salt + water (dissolved)
water boiled off saltwater (left salt).
Which two show chemical change and why?
Baking soda + vinegar and iron + sulfur when heated form new substances
Describe a simple experiment to show that an unbalanced force changes an object’s motion (list materials and the measurement you would take).
Push a toy car with different forces and measure speed or distance traveled
You drop a ball from a height. Explain how energy changes form from the moment you hold it to when it hits the ground, using the words potential and kinetic.
Holding: gravitational potential energy; falling: potential becomes kinetic; impact: kinetic becomes sound and heat
Describe how the positions of the Sun, Earth, and Moon cause a solar eclipse (brief explanation).
The Moon moves between Earth and the Sun, blocking sunlight
Explain, in one or two sentences, how the Law of Conservation of Mass applies when wood burns in a closed container.
In a closed container the mass of wood plus oxygen equals the mass of ash plus gases; mass stays the same though forms change
You mix two clear liquids and the solution becomes cloudy and gives off heat. Explain why this is likely a chemical change and how you could show mass is conserved during the change.
New properties appear (cloudiness and heat). Use a sealed container on a balance to show mass stays the same
Use evidence-based reasoning: A rolling toy car slows down and stops on a flat surface. Explain which forces act on it and why it stops.
Friction and air resistance oppose motion and convert energy to heat, causing it to stop
Design a short investigation to measure where energy goes when two toy cars collide (what you would measure and how it shows energy transfer).
Measure speed before and after, temperature change, or sound; lost kinetic energy becomes heat, sound, or deformation
Use a model or explanation: How does gravity keep the Moon orbiting Earth? Include direction of force and motion.
Gravity pulls the Moon toward Earth while its forward motion keeps it moving sideways, creating an orbit