Chemical Reactions Un-Notes

Contributor Leigh Roehm
Type Category
Instructional Materials
Demonstration , Lesson/Lesson Plan
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be “fully aligned,” the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.



Students observe the properties of substances before and after three teacher-demonstrated chemical reactions.  They use their observations to draw conclusions about characteristics that define chemical reactions.  They test their conclusions by comparing boiling water to the demonstration reactions.

Intended Audience

Educator and learner
Educational Level
  • Middle School
  • Grade 8
  • Grade 7
  • Grade 6
Access Restrictions

Free access - The right to view and/or download material without financial, registration, or excessive advertising barriers.

Performance Expectations

MS-PS1-2 Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred.

Clarification Statement: Examples of reactions could include burning sugar or steel wool, fat reacting with sodium hydroxide, and mixing zinc with hydrogen chloride.

Assessment Boundary: Assessment is limited to analysis of the following properties: density, melting point, boiling point, solubility, flammability, and odor.

This resource appears to be designed to build towards this performance expectation, though the resource developer has not explicitly stated so.

Comments about Including the Performance Expectation
This lesson is designed specifically to work toward this Performance Expectation, but not to assess it. The lesson is an introduction to chemical reactions, in which students collect data (observations) and analyze it to look for similarities between the chemical changes observed in the different reactions. They use this analysis to help them construct a definition or “rule” for identifying chemical reactions. The lesson ends there; subsequent lessons will be necessary for students to apply the “rule” to determine whether a change is physical or chemical.

Science and Engineering Practices

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
Students are asked to use their prior knowledge of the the ideas of phase change, and evidence from their observations of chemical reactions, to explain the difference between water boiling and the three chemical reactions they have observed. Teachers should watch for a common misconception that may arise - the idea that physical changes are reversible and chemical changes are not.

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
Students look for similarities and differences in their observations of the changes during three chemical reactions. The reactions are chosen so that the similarities point students toward an understanding of common signs of chemical changes. Students also use a Venn diagram to compare and contrast observations of water boiling with their observations of chemical reactions.

Disciplinary Core Ideas

This resource is explicitly designed to build towards this disciplinary core idea.

Comments about Including the Disciplinary Core Idea
The purpose of the lesson is for students to identify qualitative macro-scale changes in properties that will allow them to tell if a chemical reaction has occurred. The lesson is an introduction, and is strictly a macro-scale lesson. It does not include discussion of atoms rearranging, molecules, or of the Law of Conservation of Mass. The lesson also focuses most on the changes that happen to matter during a reaction, rather than the exact properties of the reactants and of the products.

Crosscutting Concepts

This resource is explicitly designed to build towards this crosscutting concept.

Comments about Including the Crosscutting Concept
The lesson plan asks students to make observations of changes over time during chemical reactions, including a sudden dramatic change (“iodine clock”) , and a more drawn-out process (“Elephant Toothpaste”). The lesson is an introduction, so it does not address different scales, although later in the unit the teacher could use these demonstrations as examples to show the breaking and making of new bonds in models at the atomic level.

This resource is explicitly designed to build towards this crosscutting concept.

Comments about Including the Crosscutting Concept
The lesson plan and student handout overtly refer to looking for patterns, and to using patterns to make predictions and draw conclusions. However, these are Elementary School level understandings within Patterns, so their usefulness may depend on whether students have used an NGSS curriculum during their elementary years. The Middle School understandings about Patterns are not specifically addressed in this lesson.

Resource Quality

  • Alignment to the Dimensions of the NGSS: This lesson cleaves to the spirit of NGSS in its presentation of phenomena for students to explore in order to uncover a concept. The lesson incorporates a core idea about chemical processes, though this particular lesson does not dive into atoms and molecules specifically. There is a strong reinforcement of the cross-cutting concept of Stability and Change, though again the micro-scale is not included in this lesson. Students engage in the Practice of analyzing data in order to achieve their purpose for the lesson, coming up with a definition or “rule” for chemical changes.

  • Instructional Supports: The lesson is purpose-driven, and kicks off with an activity that clarifies the purpose for students. The lesson is engaging, and supports 3-dimensional learning. Students construct and share ideas orally and by writing. The lesson plan points out possible misconceptions for teachers to watch out for, and points at which students may need more support or scaffolding in describing their observations and making connections. The lesson plan is clear about prior knowledge that students may need, and about appropriate “next steps” in a lesson sequence. Samples of student work, and videos of each demo, are instructional supports for the teacher. The lesson does not include safety tips, though the video clips show students wearing goggles and being asked not to touch the products of the reactions. Teachers will need to make sure that they can perform the demos safely. Watch out for hot gases, flame, and fumes in particular.

  • Monitoring Student Progress: The student handout and discussions are useful formative assessments. Students are specifically directed to analyze data (a Practice) and to consider how patterns can inform predictions (a CCC), in order to draw a conclusion about a core idea. Middle-level CCCs are not overt on the student handout, but could easily be added by pointing out to students that they are examining changes in an effort to explain them. Since the lesson is an introduction, a formal summative assessment is neither included nor necessary.

  • Quality of Technological Interactivity: This lesson does not involve technological interactivity.