All Things Being Equal

Contributor
Grand Valley State University, Target Inquiry
Type Category
Instructional Materials
Types
Instructor Guide/Manual , Student Guide , Experiment/Lab Activity
Note
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.

Reviews

Description

This set of a teacher and student guides provides instruction on a 2-3 day series of activities about Le Chatelier’s principle, which shows the effect of changes to conditions in an equilibrium reaction. Students work in pairs or groups to develop their concepts of equilibrium and the effects of changing the amount of reactants or products on an equilibrium system. The concepts are presented and analyzed using graphical representations, qualitative lab data, and modelling. The first part addresses the misconception that equal amounts are required for equilibrium through using a mini-activity that involves the transfer of water between beakers. The second part is a lab activity where students will see how an equilibrium system reacts to a change in concentration. The third part uses manipulatives to understand how an equilibrium operates using the mathematical equilibrium constant (Ksp) at the particulate view. The resource link takes you to the Student Guide. The Teacher Guide is available at http://www.gvsu.edu/targetinquiry/tidocuments/files/tidocuments/3DF60B5F-E041-9BB4-59AB6C95A5F3BF3A.pdf

Intended Audience

Educator and learner
Educational Level
  • High School
Language
English
Access Restrictions

Free access with user action - The right to view and/or download material without financial barriers but users are required to register or experience some other low-barrier to use.

Performance Expectations

HS-PS1-6 Refine the design of a chemical system by specifying a change in conditions that would produce increased amounts of products at equilibrium.

Clarification Statement: Emphasis is on the application of Le Chatlier’s Principle and on refining designs of chemical reaction systems, including descriptions of the connection between changes made at the macroscopic level and what happens at the molecular level. Examples of designs could include different ways to increase product formation including adding reactants or removing products.

Assessment Boundary: Assessment is limited to specifying the change in only one variable at a time. Assessment does not include calculating equilibrium constants and concentrations.

This resource is explicitly designed to build towards this performance expectation.

Comments about Including the Performance Expectation
This series of activities focuses on students developing the concept of equilibrium themselves in Part 1, but directs them to change the equilibrium by adding either a reactant or product in Part 2. In Part 3, the students use a model to understand how changes to equilibrium affect the system; this focuses on the impact that changing concentrations have on equilibrium constants, which is not within the Performance Expectation assessment boundaries. This would be a great introductory activity that students could build upon to satisfy the Performance Expectation’s redesign assessment.

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
During Part 1, the students use their graph, a text, and peer-discussion of the graph to develop and refine their idea of equilibrium. The teacher should use the exercise to address the misconception that equilibrium does not mean equal amounts using the data in Part 1. In Part 2, student may find it easier to label each test tube by number, and with a description of what is being added. The qualitative data that students collect in Part 2 provides them with the evidence they need to construct an explanation of Le Chatelier’s Principle, utilizing the equations and predictions provided in the introduction. Teachers will need to support the evolution of Le Chatelier's concept extending it to variables of pressure and temperature, and lead students towards using it to make predictions.

Disciplinary Core Ideas

This resource appears to be designed to build towards this disciplinary core idea, though the resource developer has not explicitly stated so.

Comments about Including the Disciplinary Core Idea
While this activity addresses describing changes that occur during an equilibrium shift, there is little investigation into the specific numbers of molecules present in this activity outside of Part 3. Teachers may make connection referring back to working with balanced equations, but the assessment boundaries preclude the calculations of equilibrium constants and shifts made during concentration. This activity focuses on applying Le Chatelier’s principle with a variable of concentration, but does not address the impact of temperature or pressure.

Crosscutting Concepts

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

Comments about Including the Crosscutting Concept
This resource addresses changes in matter in a system, and this cross-cutting concept would be better supported by analyzing the the lab results along with the written equilibrium equation. Additionally, teachers can use the equilibrium equation to show students how to denote shifts in equilibrium by drawing arrows to represent the changes and subsequent shifts. The resource does not address changes in the energy of a system.

Resource Quality

  • Alignment to the Dimensions of the NGSS: The strength of this series of activities is combining student driven inquiry with multiple modalities of accessing the concepts. Students use graphical representations, quantitative and qualitative data, manipulatives as models, and calculations. Teachers can move closer to the performance expectation by having students make their own changes to another equilibrium system with the desired goal of increasing the products being created.

  • Instructional Supports: The teacher guide has many suggestions and tips on preparation and implementation of these activities. Teacher should also modify to scaffold students to working toward the math skills used in Part 3. Teachers can modify to have students work in pairs, teams, or even do the first part as a demonstration.

  • Monitoring Student Progress: There are “teacher checks” printed within the student packet, but the teacher will need to be active in checking in with each group as they progress through each part. The teacher should have students report out throughout each part to address misconceptions and develop a better understanding of equilibrium systems. There is no formative assessment, although one packet could be collected for each group or a final lab report could be produced as a ending assessment. ELL students will require a preview of important vocabulary, and may be partnered with a native speaker to help digest the dense writing within this student guide. Teachers may need to demonstrate the first few cycles of the activity in Part 1, as the directions may be confusing to some students.

  • Quality of Technological Interactivity: Teachers should utilize graphing software in Part 1 to have students add the technology aspect to analyzing their data and producing a digital graph.