MS-PS1-5

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Develop and use a model to describe how the total number of atoms does not change in a chemical reaction and thus mass is conserved.

Clarification statement: Emphasis is on the law of conservation of matter and on physical models or drawings, including digital forms, that represent atoms.

Assessment boundary: Assessment does not include the use of atomic masses, balancing symbolic equations, or intermolecular forces.

Grade 8 Science Test Questions

Released New York State Grade 8 science test questions that assess MS-PS1-5 are listed here by test and question cluster. Each link opens the question with its answer key.

Exam	Cluster	Question
Spring 2026 Grade 8 Test	Ammonia and the Nitrogen Cycle	Question 26
	Hard-Boiled Eggs	Question 42
Spring 2025 Grade 8 Test	Rust	Question 25
Spring 2024 Grade 8 Test	The Chemistry of Propane	Question 51
Middle school sample clusters	Investigating Chemical Reactions	Question 3

Vocabulary

Terms from the Middle School Science Glossary that come from this standard or from the released Grade 8 Science Test questions that assess it.

From this standard

• atom
• atomic mass
• balanced equation
• chemical reaction
• conservation of mass
• evidence
• intermolecular force
• law of conservation of matter
• mass
• matter
• model
• molecule
• new substance
• physical model
• property
• rearrange
• symbolic equation
• type of atom

From released test questions

• atmosphere – Spring 2026
• burning – Spring 2024
• chemical property – Spring 2026
• claim – Spring 2026, Sample
• closed system – Sample
• conservation of matter – Spring 2024
• data table – Spring 2026
• element – Spring 2025
• energy – Spring 2024
• equation – Sample
• gas – Spring 2026, Sample
• heat – Sample
• investigation – Sample
• kinetic energy – Spring 2026
• liquid – Sample
• physical property – Spring 2026
• product (of a reaction) – Spring 2025, Sample
• reactant – Spring 2025
• reaction – Spring 2024, Sample
• soil – Spring 2026
• solid – Sample
• substance – Spring 2026, Sample
• volume – Spring 2024

Performance Level Descriptions

Every Grade 8 Science Test question on MS-PS1-5 is written to match one of the performance level descriptions (PLDs) below.

Level 1: Given a model showing a chemical reaction, identify evidence that proves the total number of atoms is conserved. Spring 2026 Question 26, Spring 2026 Question 42, Spring 2025 Question 25, Spring 2024 Question 51

Level 2: Given a model, describe how the total number of each type of atom does not change in a chemical reaction and/or that mass is conserved. Sample Investigating Chemical Reactions Question 3

Level 3: Develop and use a model to describe how the total number of atoms does not change in a chemical reaction and thus mass is conserved.

Level 4: Develop and use a model (including balanced equations and/or atomic masses) to describe how the total number of each type of atom does not change in a chemical reaction and because of this, mass is conserved.

Notice: PLD levels!

Resources

Examples and discussion of resources for the learning, teaching, and assessment of MS-PS1-5.

This section could be expanded upon. You can help out by adding to this section.

NGSS Dimensions

Performance expectation MS-PS1-5 was developed using the following elements from the NRC document A Framework for K-12 Science Education:

Science and Engineering Practices

• Developing and Using Models
  • Develop a model to describe unobservable mechanisms.

Disciplinary Core Ideas

• PS1.B: Chemical Reactions
  • (NYSED) Substances react chemically in characteristic ways. When substances react, the atoms that make up the molecules rearrange, forming new substances with different properties.
  • The total number of atoms does not change in a chemical reaction and thus mass is conserved.

Crosscutting Concepts

• Energy and Matter
  • Matter is conserved because atoms are conserved in physical and chemical processes.

Page contributors: Conrad Richman, Caroline Leonard, Shirley Shameen

MS | MS. Chemical Reactions