Matter Check In Test Paper North Carolina Science Assessment System
Grade 8 Science Check-In: Matter & Mixtures
Score _____ / 25
Name: _________________________________
Date: ____________________
Period: __________
Directions: Read each scenario and data set carefully. For Part I, select the best answer choice. For Part II, provide complete, evidence-based written responses.
Standard 8.P.1
Part I: Selected-Response Questions (Target Skills 1–6)
1
A student tests three unknown solid mineral samples in the laboratory and records their physical properties in the table below.
Sample
Mass (g)
Density (g/cm³)
Melting Point (°C)
Electrical Conductivity
Mineral W
12.4
2.70
660
High
Mineral X
24.8
2.70
660
High
Mineral Y
12.4
8.96
1,085
High
Which conclusion is supported by the data in the table?
A Mineral W and Mineral X are composed of the same substance because their characteristic properties match.
B Mineral W and Mineral Y are composed of the same substance because they have identical sample mass.
C Density and melting point are extensive properties that increase as the sample mass doubles.
D Electrical conductivity is the only physical property that can identify an unknown solid.
2
Two clear liquids, Sample A and Sample B, are heated until they boil. Sample A boils at a constant 100°C from start to finish. Sample B boils over a rising temperature range from 102°C to 109°C, leaving a white crystalline residue in the beaker. Which statement is supported by this evidence?
A Sample A is a heterogeneous mixture, and Sample B is a pure compound.
B Sample A is a pure substance, and Sample B is a homogeneous mixture.
C Both samples are pure substances because both began as completely clear liquids.
D Both samples underwent chemical changes because boiling requires heat input.
3
A science class sorts matter samples using observed property patterns shown in the chart below:
Class 1 Single type of atom only;
Class 2 Fixed ratio of bonded atoms;
Class 3 Variable composition of substances;
Which sample is correctly matched to its classification?
A Pure iron metal (Fe) belongs in Class 2 as a compound.
B Distilled water (H₂O) belongs in Class 2 as a pure compound.
C Table salt dissolved in water belongs in Class 1 as an element.
D Pure oxygen gas (O₂) belongs in Class 3 as a physical mixture.
Grade 8 Science NC Check-In • Test Form A Go on to the next page →
Grade 8 Science NC Check-In: Matter & Mixtures Name: _________________________________
4
A student places 15 grams of dark gray iron filings and 10 grams of bright yellow sulfur powder into a beaker and stirs them thoroughly at room temperature. Which statement best describes how the substances are combined?
A The substances are physically combined, so the iron retains its magnetism and the sulfur retains its yellow color.
B The substances chemically react to form a new compound with completely different chemical properties.
C The total mass of the mixture is less than 25 grams because physical blending destroys mass.
D The substances form chemical bonds that require chemical reactions to separate.
5
Four everyday mixtures are examined in science class. Which row in the table correctly classifies all four mixtures based on observable distribution patterns?
Option
Brass Alloy
Salt Water Solution
Pond Water with Silt
Vegetable Salad
A
Heterogeneous
Homogeneous
Heterogeneous
Homogeneous
B
Homogeneous
Homogeneous
Heterogeneous
Heterogeneous
C
Homogeneous
Heterogeneous
Homogeneous
Heterogeneous
D
Heterogeneous
Heterogeneous
Homogeneous
Heterogeneous
6
A teacher gives a lab group a beaker containing sand, salt, and water. Which sequence of physical processes will separate all three components into pure, individual substances?
A Pass the mixture through filter paper to collect sand, then evaporate the liquid to collect dry salt and condense the water.
B Use a bar magnet to pull out the salt, then boil the water to leave dry sand behind.
C Filter the mixture twice: once to trap the salt crystals and once to trap the sand grains.
D Heat the mixture until a chemical reaction destroys the water and leaves dry salt and sand.
Part II: Written-Response & CER Questions (Questions 7–9)
7
Laboratory Investigation: A student tests an unknown crystalline white powder (Sample Z). When 10 grams of Sample Z is dissolved in 50 mL of water, the liquid turns slightly cloudy. After filtering through fine filter paper, 2.5 grams of white solid remains on the paper, while a clear liquid passes through into the flask. When the clear liquid is boiled dry, 7.5 grams of identical white crystals remain.
Part A: Identify one qualitative physical property and one quantitative physical property of Sample Z reported in the investigation.
Part B: State a claim determining whether Sample Z is a pure substance or a mixture. Provide evidence and scientific reasoning from the lab results to justify your claim.
Grade 8 Science NC Check-In • Test Form A Go on to the next page →
Grade 8 Science NC Check-In: Matter & Mixtures Name: _________________________________
8
Physical Mixtures vs. Chemical Compounds: In Investigation 1, a student stirs iron filings and sulfur powder in test tube A at room temperature. In Investigation 2, the student strongly heats an identical mixture in test tube B using a Bunsen burner, producing a solid black chunk of iron sulfide (FeS).
Part A: When a bar magnet is passed near test tube A, all of the iron filings are easily pulled away from the sulfur. However, when the magnet is passed near test tube B, none of the iron separates. Explain this observation by describing how the substances are combined in test tube A compared to test tube B.
Part B: If a student dissolves 12 grams of sugar into a beaker containing 100 grams of pure water, what is the total mass of the resulting mixture? Explain how this demonstrates the physical combination of matter and the law of conservation of mass.
9
Laboratory Separation Challenge: Your lab group receives a beaker containing a mixture of coarse sand, iron filings, dissolved table salt, and 100 mL of water.
Part A: Classify the mixture in the beaker as either homogeneous or heterogeneous . Cite one specific observable piece of evidence to support your classification.
Part B: Write a step-by-step scientific procedure to separate all three solid components (iron filings, sand, and salt) from the water so that each substance is isolated. For each step, identify the physical tool or technique used and the specific physical property that makes the separation possible.
Step 1 (Separate Iron Filings):
Physical Property Utilized:
Step 2 (Separate Sand from Salt Water):
Physical Property Utilized:
Step 3 (Separate Salt from Water):
Physical Property Utilized:
Grade 8 Science NC Check-In • Test Form A STOP • End of Assessment
Matter Check In Answer Key Educator Scoring Guide & Master Rubric
Grade 8 Science Check-In: Matter Answer Key
North Carolina Standard Course of Study Science • Standard 8.P.1 (Total Points: 25)
Teacher Edition Form A Key • 8th Grade
Part I Quick Key:
Q1: A (2 pts) Q2: B (2 pts) Q3: B (2 pts) Q4: A (2 pts) Q5: B (2 pts) Q6: A (2 pts)
Part I: Selected-Response Rationales & Distractor Analysis (12 Points)
Question 1 • Target 1 (Physical Properties) Correct: A
Rationale: Density and melting point are characteristic (intensive) properties. W and X have identical density (2.70 g/cm³) and melting point (660°C), proving they are the same substance despite differing masses.
Distractors: B confuses extensive property (mass) with identity; C wrongly claims intensive properties change with sample size; D falsely restricts identification to conductivity.
Question 2 • Target 2 (Pure vs. Mixture) Correct: B
Rationale: Pure substances display a constant boiling plateau at standard pressure (Sample A at 100°C). Solutions boil over a temperature range and leave dissolved solute residue upon evaporation (Sample B).
Distractors: A inverts the classifications; C relies on misleading visual clarity; D confuses phase changes (physical) with chemical changes.
Question 3 • Target 3 (Classifying Substances) Correct: B
Rationale: Water (H₂O) consists of chemically bonded hydrogen and oxygen atoms in a fixed 2:1 ratio that cannot be physically separated, perfectly matching Class 2 (Compound).
Distractors: A misidentifies an element as a compound; C places a mixture in element class; D labels a diatomic element (O₂) as a mixture.
Question 4 • Target 4 (Mixture Combination) Correct: A
Rationale: Mixing at room temperature causes only physical combination. Substances retain their original physical properties (magnetism, color) and can be separated physically.
Distractors: B and D assume heating/chemical reaction took place; C violates the law of conservation of mass.
Question 5 • Target 5 (Homo vs. Hetero) Correct: B
Rationale: Brass (solid solution/alloy) and salt water are uniform throughout (homogeneous). Pond water (suspended silt settles) and vegetable salad have distinct visible phases (heterogeneous).
Distractors: A, C, and D misclassify solid alloys or liquid solutions as heterogeneous.
Question 6 • Target 6 (Physical Separation) Correct: A
Rationale: Filtration separates insoluble sand based on particle size. Evaporation/distillation separates dissolved salt and water based on differences in boiling point.
Distractors: B assumes salt is magnetic; C claims dissolved salt can be trapped by filter paper; D incorrectly invokes chemical reactions.
Question 7 Scoring Rubric • Targets 1 & 2 (Total: 4 Points) Constructed Response
Part A: Physical Properties Identification 2 Points Max
1 pt: Correctly names one qualitative property (e.g., white color, crystalline texture, cloudy appearance).1 pt: Correctly names one quantitative property with units and measurement method (e.g., 10 grams of mass measured on a balance; 50 mL of volume measured in a graduated cylinder).
Student Exemplar: "Qualitative property: white crystalline solid. Quantitative property: 10 grams of solid mass, which was measured using an electronic balance."
Part B: Claim-Evidence-Reasoning (CER) 2 Points Max
1 pt: States correct claim that Sample Z is a mixture .1 pt: Cites lab evidence that it was separated by physical filtration (2.5 g insoluble residue) and boiling (7.5 g dissolved crystals), proving multiple distinct substances with different solubilities.
Student Exemplar: "Claim: Sample Z is a mixture. Evidence: Filtration separated 2.5 g of insoluble solid, and boiling separated 7.5 g of dissolved solid. Reasoning: Pure substances cannot be split into different components by physical filtering or boiling."
Grade 8 Science NC Check-In • Master Scoring Guide Page 1 of 2
Grade 8 Science NC Check-In: Master Scoring Guide & Rubrics Standard 8.P.1 • Matter: Properties and Change
Question 8 Scoring Rubric • Targets 3 & 4 (Total: 4 Points) Constructed Response
Part A: Physical Blend vs. Chemical Bond 2 Points Max
1 pt: Explains that test tube A is a physical mixture where no chemical bonds formed, allowing iron to retain its individual magnetic property.1 pt: Explains that test tube B underwent a chemical reaction forming iron sulfide (FeS), a compound where bonded iron loses its individual magnetic property.
Student Exemplar: "In test tube A, iron and sulfur are only physically mixed. No bonds formed, so iron keeps its magnetism. In test tube B, heating caused a chemical reaction forming FeS, bonding the atoms so magnetic properties were lost."
Part B: Mass Conservation in Mixtures 2 Points Max
1 pt: Correctly states the total mass is exactly 112 grams (12 g sugar + 100 g water).1 pt: Explains that dissolving is a physical change where no atoms are created or destroyed, demonstrating conservation of mass.
Student Exemplar: "The total mass is 112 grams. Dissolving sugar in water is a physical change. Sugar molecules disperse evenly between water molecules, but no mass is lost or destroyed."
Question 9 Scoring Rubric • Targets 5 & 6 (Total: 5 Points) Extended Lab Design Response
Part A: Heterogeneous Classification (2 Points) 2 Points
1 pt: States that the mixture in the beaker is heterogeneous .1 pt: Cites observable evidence: solid grains of sand and iron filings do not dissolve and form distinct, visible solid layers or settle at the bottom.
Part B: 3-Step Physical Separation Procedure (3 Points) 3 Points
Step 1: Separate Iron (1 pt) Pass a magnet over/through the mixture to pull out iron filings.Property: Magnetism / magnetic attraction.
Step 2: Separate Sand (1 pt) Pour remaining mixture through filter paper and funnel.Property: Particle size / insolubility in water.
Step 3: Separate Salt & Water (1 pt) Heat/boil salt solution in an evaporating dish or distillation flask.Property: Boiling point difference.
NC Achievement Level Conversion & Diagnostic Matrix
25 total raw points
Level 1–2: Not Proficient 0 – 14 Points
Reteach intensive properties, definition of pure substance, and physical separation techniques.
Level 3: Sufficient 15 – 18 Points
Demonstrates grade-level recall; needs support citing CER evidence and multi-step lab procedures.
Level 4: Proficient 19 – 22 Points
Solid mastery of NC 8.P.1 targets; distinguishes physical combinations from chemical compounds.
Level 5: Advanced 23 – 25 Points
Superior command of matter standards; generates precise scientific rationales and complete lab designs.
Grade 8 Science NC Check-In • Master Scoring Guide Page 2 of 2
Matter Check In Slides NC 8th Grade Science • Standard 8.P.1
Review & Answer Key
NC Check-In • EOG Test Debrief
Matter: Properties, Pure Substances & Mixtures
Mastering physical property patterns, classification of matter, and physical separation techniques with complete item walkthroughs.
6 Selected-Response Items
3 Constructed-Response CERs
Scoring Rubric & Explanations
Target 1
Physical Properties of Matter
Question 1 Review
Key Concept
Intensive vs. Extensive Properties
Characteristic (Intensive) properties such as density and melting point never change with sample size.
Extensive properties (mass, volume) change whenever sample amount changes and cannot identify a substance alone.
Rule: If density and melting point match, the substances match!
Question 1 Walkthrough Correct: A
Mineral W (12.4 g) and Mineral X (24.8 g) both have a density of 2.70 g/cm³ and melting point of 660°C.
Why A is Correct: Despite having different masses, Mineral W and Mineral X share identical characteristic properties, proving they are the same mineral (aluminum).
Distractor Trap: Mass does not define a substance's identity!
Standard 8.P.1 • Matter: Properties and Change Slide 2 of 8
Target 2
Pure Substance vs. Mixture Evidence
Questions 2 & 7 Review
Observable Evidence
Heating Curves & Residue
Pure Substance: Boils at a sharp, constant plateau (100°C flat line). Leaves zero residue.Liquid Mixture: Boils over a rising temperature range (102°C–109°C) as solvent evaporates.Filtration Residue: Solute residue after physical separation proves multiple components.
CER Tip: Never say "it looks clear." Visual clarity does not prove purity!
Questions 2 & 7 Answers Q2: B
Question 2 Key: Sample A boiled at constant 100°C (pure). Sample B boiled 102°C–109°C and left residue (homogeneous solution).
Question 7 CER Key: Sample Z is a mixture because physical filtration separated 2.5 g insoluble solid and boiling separated 7.5 g crystals.
• Full credit requires linking physical separation to mixture definition.
Standard 8.P.1 • Matter: Properties and Change Slide 3 of 8
Target 3
Classifying Matter by Patterns
Question 3 Review
Class 1
Elements
Composed of only one type of atom .
• Iron metal (Fe)
• Oxygen gas (O₂)
• Gold (Au)
Cannot be physically or chemically broken into simpler substances.
Class 2 (Q3 Key)
Compounds
Atoms chemically bonded in a fixed ratio.
• Water (H₂O) ← Correct!
• Carbon dioxide (CO₂)
• Table salt (NaCl)
Cannot be separated physically; requires a chemical reaction.
Class 3
Mixtures
Substances physically blended in variable ratios.
• Salt water solution
• Air (N₂, O₂, Ar, CO₂)
• Brass alloy
Can always be separated by physical methods.
Standard 8.P.1 • Matter: Properties and Change Slide 4 of 8
Target 4
How Substances in Mixtures Combine
Questions 4 & 8 Review
Question 4 & 8A Focus
Physical Blend vs. Bond
Mixture (Stirred at Room Temp): Iron + Sulfur retains individual properties. A magnet easily pulls iron out. No chemical bonds exist! (Q4 Key: A)
Compound (Strongly Heated): Iron + Sulfur chemically react to form iron sulfide (FeS). Bonded iron loses its magnetism!
Question 8B Focus
Conservation of Mass
12 g Sugar + 100 g Water = 112 g Solution
Why Mass Does Not Change: Dissolving is purely a physical change. Sugar molecules disperse evenly between water molecules, but no atoms disappear or are created.
• Never let students say "dissolved sugar lost weight"!
Standard 8.P.1 • Matter: Properties and Change Slide 5 of 8
Target 5
Homogeneous vs. Heterogeneous
Question 5 Review
Uniform Single Visible Phase
Homogeneous (Solutions)
Particles are distributed evenly at the molecular level . Every sample taken has identical composition.
• Salt Water: Fully dissolved ions
• Brass Alloy: Solid solution (Copper + Zinc)
• Filtered Air: Gaseous solution
Non-Uniform Distinct Phases
Heterogeneous (Suspensions)
Particles are unevenly distributed and easily distinguishable. Heavy particles often settle over time.
• Pond Water: Suspended silt settles out
• Vegetable Salad: Visible different parts
• Oil & Water: Immiscible liquid layers
✓ Question 5 Master Key: Option B Brass & Salt Water = Homogeneous • Pond Water & Salad = Heterogeneous
Standard 8.P.1 • Matter: Properties and Change Slide 6 of 8
Target 6
Separation by Physical Means
Questions 6 & 9 Review
Step 1 Magnetism
Separate Iron
Pass a bar magnet over the mixture to extract iron filings.
Property: Magnetic attraction (iron is ferromagnetic; sand and salt are not).
Step 2 Filtration
Separate Sand
Pour liquid through filter paper in a funnel.
Property: Particle size & water insolubility (sand stays on paper; dissolved ions pass through).
Step 3 Evaporation
Separate Salt
Heat filtrate in evaporating dish or distillation flask.
Property: Boiling point difference (water boils at 100°C; salt melts at 801°C and remains).
✓ EOG Item Rule: Every physical separation must name the underlying physical property driving the process!
Standard 8.P.1 • Matter: Properties and Change Slide 7 of 8
NC Check-In & EOG Mastery Checklist
Test Success Strategies
1
Check the Curve
Flat phase change line = pure substance.
2
Preserve the Mass
In every physical mixture, total mass before mixing strictly equals total mass after mixing.
3
Name the Property
In written responses, never just name the tool (filter, magnet)—always cite density, magnetism, or boiling point !
NC Standard Course of Study Science • 8.P.1 Structure and Properties of Matter Classroom Ready • End of Slide Deck
