Page 1 of 2 • Matter Mastermind Teacher Key
Exemplars & Scoring Guidance
Part 3 Short Answer Exemplars
Q4 Exemplar (Cutting 600g Silver Block):
"When the block is cut into three equal pieces, both the mass and the volume decrease by a factor of 3 (\(200\text{ g}\) and \(V/3\)). Because density is calculated as \(D = m/V\), the ratio remains exactly \(10.49\text{ g/cm}^3\). At the molecular level, the silver atoms remain packed with the exact same spacing and atomic mass."
Q5 Exemplar (Boiling Water Temperature Plateau):
"During a phase change, the continuous heat input is converted into potential energy to overcome the intermolecular attractions holding liquid water molecules together, transforming them into vapor. The average kinetic energy (temperature) does not increase until the liquid has completely transitioned into steam."
Part 4 Application Scenarios Key
Scenario A: Density Column
Scenario B: Mystery White Powder
Part 5: CER Synthesis Rubric & Exemplar Response
CLAIM: The student's claim is scientifically invalid. Mass alone cannot identify whether a metal is iron or aluminum.
EVIDENCE: Mass is an extensive property dependent on sample size; a large piece of aluminum can have the exact same mass as a smaller piece of iron (e.g., both 100g). Iron has a density of \(7.87\text{ g/cm}^3\) while aluminum has a density of \(2.70\text{ g/cm}^3\).
REASONING: To identify a pure substance, scientists must use characteristic (intensive) properties like density (\(D=m/V\)), which combines mass and volume into a constant ratio unique to each element.
| Component | Proficient (2 pts) | Developing (1 pt) | Needs Improvement (0 pts) |
|---|---|---|---|
| Claim | Directly refutes prompt with scientific clarity. | Unclear or partially stated claim. | Incorrect or missing claim. |
| Evidence | Cites both mass as size-dependent and density/volume. | Mentions mass or density without specific contrast. | No relevant text evidence cited. |
| Reasoning | Accurately connects intensive vs extensive properties. | Vague explanation of why mass is insufficient. | Missing scientific principle. |
Common Student Misconceptions & Facilitation Tips:
Misconception 1: "Heavier objects are always denser." Clarification: Emphasize that a heavy log floats while a tiny pebble sinks because density is mass divided by volume, not total weight.
Misconception 2: "Dissolving is a chemical change because the solute disappears." Clarification: Remind students that evaporating the water recovers the original solute crystals, proving no chemical bonds were broken.
Page 2 of 2 • Matter Mastermind Teacher Key
Part 1: Guided Matter Sorting Matrix
Use Word Bank Below
Definitions: [One type of atom] • [Two+ atoms chemically bonded] • [Evenly blended mixture] • [Uneven layers] Examples: Pure Gold (\(\text{Au}\)) • Water (\(\text{H}_2\text{O}\)) • Saltwater • Oil and Water
| Category | Scientific Meaning (Fill in) | Real Example (Fill in) |
|---|---|---|
| Pure Element | Made of only one type of atom | _______________________________ |
| Chemical Compound | Two or more atoms ___________________ | _______________________________ |
| Homogeneous Mixture | Substances mixed evenly / uniformly | _______________________________ |
| Heterogeneous Mixture | Substances mixed with _________________ | _______________________________ |
Physical Properties (Circle 2):
Density (\(D=m/V\)) Flammability Solubility
Chemical Properties (Circle 2):
Reactivity with acid Melting point Rusting / Oxidation
Page 1 of 3 • Matter Mastermind Guided Packet
Supported Edition
Directions: Match each word to its definition by writing the letter in the bracket. Use the hint clues!
A. Density (Mass \(\div\) Volume)
B. Solubility (Dissolving ability)
C. Kinetic Energy (Motion energy)
D. Sublimation (Solid to gas directly)
E. Chemical Property (Makes new substance)
F. Intensive Property (Size does not matter)
[ ] 1.
When solid dry ice turns straight into a gas without melting into a liquid.
[ ] 4.
A property like density that stays the same whether you have 1g or 1,000g.
[ ] 2.
The ability of sugar or salt to completely dissolve into warm water.
[ ] 5.
The energy of moving particles, which increases when matter gets hotter.
[ ] 3.
How tightly packed the particles are inside an object (\(D = m/V\)).
[ ] 6.
A trait that describes how matter can react to form a brand new substance.
1. Why is density better than mass for identifying an unknown metal? (Hint: Think about sample size)
AMass changes when heated, but density is always zero.
BThe mass-to-volume ratio (\(D = m/V\)) stays the same for any sample size.
CMass is a chemical property that changes every minute.
DDensity is only used for gases, not metals.
2. Which of the following is a chemical property (creates a brand new substance)?
AWater freezing into ice cubes at 0°C.
BA piece of wood burning in fire and producing ash and smoke.
CSugar dissolving into a cup of hot tea.
DMelting an aluminum soda can into liquid metal.
3. Guided Explanation: If a 600g pure silver block is cut in half into two 300g pieces, explain why the density of each piece is still \(10.49\text{ g/cm}^3\).
When the silver block is cut in half, its mass becomes smaller, but its volume also ___________________.
Because density is calculated by dividing mass by volume (\(D = m/V\)), the ratio stays ________________.
4. Guided Evidence: Why does boiling water stay at 100°C even while the stove continues adding heat?
The extra heat energy is being used to ___________________________________________________________
(Hint: Think about breaking water molecules apart into steam vapor).
Page 2 of 3 • Matter Mastermind Guided Packet
Real-World Challenges
Scenario A: Guided Density Tower Rule: Low density floats on high density
Three liquids are poured into a cylinder: Honey (\(1.42\text{ g/cm}^3\)), Water (\(1.00\text{ g/cm}^3\)), and Oil (\(0.92\text{ g/cm}^3\)).
Liquid Layers (Fill from lowest to highest density):
1. Top Layer (Lowest Density): ___________________
2. Middle Layer: _________________________________
3. Bottom Layer (Highest Density): ________________
Where will these objects land? (Circle one):
• Oak Bead (\(0.85\text{ g/cm}^3\)): [ Floats at top / Sinks to bottom ]
• Rubber (\(1.15\text{ g/cm}^3\)): [ Rests on Honey / Floats on Oil ]
Scenario B: Forensics Powder Test Clue Table
• Cornstarch: Does not dissolve; No fizz
• Sugar: Dissolves in water; No fizz
• Baking Soda: Dissolves; Fizzes with vinegar
Lab Result: The mystery powder dissolved in water AND fizzed vigorously with vinegar.
1. The mystery powder must be: ___________________________________________________________
2. Fizzing with vinegar is a [ Physical / Chemical ] property because a new gas was formed.
Part 5: Structured Scientific Argument (CER Frame)
Sentence Stems
Prompt: A student says: "Measuring mass alone is enough to tell iron and aluminum apart." Complete the CER below:
CLAIM (Choose one):
The student is [ correct / incorrect ] because mass alone [ can / cannot ] identify a metal.
EVIDENCE (Fill in the blanks):
According to the text, mass changes depending on sample ___________________. A piece of iron and a piece of aluminum can both weigh exactly ___________________ grams.
REASONING (Fill in the scientific principle):
To identify an unknown substance, scientists must use density (\(D = m/V\)) because density is an ___________________ property that stays constant regardless of sample size.
Page 3 of 3 • Matter Mastermind Guided Packet
500g Pure Copper Bar: \(D = 8.96\text{ g/cm}^3\)
5g Pure Copper Wire: \(D = 8.96\text{ g/cm}^3\)
Floating Rule: Substances with density \(< 1.00\text{ g/cm}^3\) float in water; \(> 1.00\text{ g/cm}^3\) sink. Slide 4 of 7
Thermal Dynamics
SOLID Low Kinetic Energy
\(\rightarrow\) Heat added: Melting
LIQUID Medium Energy
\(\rightarrow\) Heat added: Vaporization
GAS High Kinetic Energy
Solid \(\rightarrow\) Gas directly: Sublimation
Crucial: During boiling/melting, temperature stays flat while energy breaks particle attractions. Slide 5 of 7
Application Scenarios
Density Test
You have three non-mixing liquids:
• Honey: \(1.42\text{ g/cm}^3\) (Heaviest \(\rightarrow\) Bottom)
• Water: \(1.00\text{ g/cm}^3\) (Middle)
• Corn Oil: \(0.92\text{ g/cm}^3\) (Lightest \(\rightarrow\) Top)
Where will a rubber stopper (\(1.15\text{ g/cm}^3\)) rest?
Reactivity Test
An unknown white powder dissolves in water and fizzes violently when exposed to vinegar:
• Dissolving in water: Physical Property (Solubility)
• Fizzing with vinegar: Chemical Property (Reaction)
Identification: Baking Soda (\(\text{NaHCO}_3\)) producing \(\text{CO}_2\) gas!
Use both physical and chemical tests together to achieve 100% positive identification! Slide 6 of 7
Scientific Communication
C
A direct statement answering the scientific question.
"Mass alone cannot identify whether an unknown metal is iron or aluminum."
E
Scientific data, observations, or text facts.
"Mass varies with sample size; a block of iron and aluminum can both weigh 100 grams."
R
Connecting evidence to the overarching science principle.
"To identify substances, we need intensive properties like density (\(D=m/V\)) that stay constant."
Ready to complete your Matter Mastermind investigation packet! Slide 7 of 7
Self-Check Confidence: 1 - Still Confused 2 - Getting There 3 - Matter Master!
Matter Mastermind • Quick Formative Assessment
