Matter Detectives Worksheet
Grade 5 Science Physical Science • Matter Unit
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Matter Detectives: Changes & Conservation
Read the scientific briefing below carefully, then proceed to the investigation questions on page 2.
1. The Building Blocks of Everything
Everything in our universe that takes up space and has mass is made of matter. Matter is built from tiny particles called atoms and molecules that are far too small to see with the naked eye. Whether you are observing a solid block of ice, a glass of water, or the invisible air inside a balloon, matter is always present and active.
2. Physical Changes: Shifting Shapes and States
A physical change occurs when matter alters its physical properties—such as shape, size, or state (solid, liquid, gas)—without turning into an entirely new substance. For example, when an ice cube melts into liquid water, its appearance and temperature change, but its particles are still water molecules (\(\text{H}_2\text{O}\)). Dissolving table salt into warm water, tearing a sheet of paper, or crushing an aluminum can are also physical changes because no new chemical substances are created.
3. Chemical Changes: Creating New Substances
A chemical change happens when particles rearrange to form one or more brand-new substances with different properties. Scientists look for clear evidence of a chemical reaction, such as a color change, the release of gas bubbles, temperature change (giving off heat or getting cold), or the production of light or odor. When iron reacts with oxygen to form rust, or when baking soda mixes with vinegar to create carbon dioxide gas, a chemical change has occurred.
4. The Law of Conservation of Matter
One of the fundamental rules of science is that matter cannot be created or destroyed during any physical or chemical process. This principle is called the Conservation of Matter. The total weight of all starting materials (reactants) will always equal the total weight of all ending materials (products), as long as nothing escapes. Even if ice melts or wood burns to ash and gas in a closed system, every single particle is still accounted for!
Physical Change Clue:
Same substance remains; reversible state or size changes (melting, dissolving, chopping).
Chemical Change Clue:
New substance forms; signs include bubbling gas, color change, rust, or heat.
Comprehension Check
Investigating Matter: Read & Respond
Score: _____ / 5
Directions: Read each question carefully and fill in the bubble beside the best answer choice.
1. A student places 50 grams of ice cubes into a tightly sealed ziplock bag. After the ice melts completely into liquid water, what will the total weight of the bag and water be?
A Less than 50 g because liquid is lighter than solid ice
B Exactly 50 g because no matter was created or destroyed
C More than 50 g because water expands when warmed
D 0 g because the ice underwent a chemical change
2. Which of the following is the best example of a chemical change rather than a physical change?
A Chopping a carrot into tiny pieces for soup
B Freezing fruit juice to make an ice pop
C Baking soda reacting with lemon juice to release gas
D Stirring chocolate powder into cold milk
3. Maya dissolves 15 grams of sugar into 200 grams of warm water until the sugar is completely invisible. What is the total mass of the sugar water solution?
A 185 grams
B 200 grams
C 215 grams
D 300 grams
4. Which observation provides the strongest evidence that a chemical reaction has taken place?
A A solid candle wax block softens when placed under warm sun
B Two clear liquids mix together and produce gas bubbles and heat
C Water vapor in the air condenses onto a cold window pane
D Sand and water are combined inside an open plastic bucket
5. A scientist mixes 20 grams of vinegar and 5 grams of baking soda inside an open beaker. When measured afterward, the mixture weighs only 23 grams. Why did the mass decrease?
A 2 grams of gas escaped into the surrounding air
B Matter was completely destroyed by the reaction
C Baking soda loses mass whenever it gets wet
D The scale stopped working during the chemical test
Scientist's Quick Reflection: Explain in 1 sentence
In your own words, why does the total weight stay the same when water freezes into ice?
