Changes of State

Contributor
American Chemical Society
Type Category
Instructional Materials
Types
Simulation , 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 is the second chapter in the American Chemical Society (ACS)  program Middle School Chemistry. This chapter contains five lessons or activities:

  1. Heat, Temperature, and Conduction

  2. Changing State—Evaporation

  3. Changing State—Condensation

  4. Changing State—Freezing

  5. Changing State—Melting

Each lesson is outlined in a detailed lesson plan that follows the BSCS 5E instructional model. The exploration phase usually contains student activities followed in the explanation phase with a simple simulation that illustrates the particle behavior during  conduction in the first lesson and during a phase change in the following lessons. The first lesson provides important background knowledge necessary to understand how energy is transferred in the subsequent phase changes.

Each lesson is outlined comprehensively in the lesson plan with extensive supporting materials such as background readings, student readings, and a chapter overview lecture. Each lesson begins with a series of questions as a way of helping students design an experiment. A well described experiment follows. The simulation that illustrates water molecules at different temperature is introduced to explain the observations in the experiment. The explanation is often extended with an additional activity on a closely related topic.

The website includes downloadable pdf documents for the lesson plans, the

entire chapter, student activity sheets and the answer sheet for the activity sheet and a student reader to be used at the end of the lesson.

Intended Audience

Educator
Educational Level
  • Middle School
Language
English
Access Restrictions

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

Performance Expectations

MS-PS1-4 Develop a model that predicts and describes changes in particle motion, temperature, and state of a pure substance when thermal energy is added or removed.

Clarification Statement: Emphasis is on qualitative molecular-level models of solids, liquids, and gases to show that adding or removing thermal energy increases or decreases kinetic energy of the particles until a change of state occurs. Examples of models could include drawing and diagrams. Examples of particles could include molecules or inert atoms. Examples of pure substances could include water, carbon dioxide, and helium.

Assessment Boundary: none

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

Comments about Including the Performance Expectation
The explanation in the lessons describes the motion of the molecule/particle as being related to average kinetic energy or just energy. The term thermal energy is not used. This could be easily corrected by pointing out that the kinetic energy associated with motion in the simulations and explanation is also called thermal energy. The objectives of the five lesson all call for students to explain phenomena, such as evaporation, condensation, and melting and freezing at the molecular or atomic level. Lesson 1 expects students to develop a model but the other lessons avoid the term. Through the use of animations or simulations, students are introduced to the idea of models with only limited use of the term and idea. There is no discussion or explanation of models. Introducing the idea and terminology explicitly could easily be added to each lesson in the explanation and elaboration phase.

Science and Engineering Practices

Disciplinary Core Ideas

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

Comments about Including the Disciplinary Core Idea
The inclusion of pressure as a variable in phase change will require additional lessons with experiments that are difficult to carry out in most classrooms. A simulations and an accompanying lessons is available at http://phet.colorado.edu/en/simulation/states-of-matter-basics.

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

Comments about Including the Disciplinary Core Idea
The introduction of the the phenomena of evaporation and condensation through experiments in Lessons 2 and 3 followed by animations that provide models for liquids and gases make this core idea clear to students. In addition, a model for molecular motion during a change of state is well illustrated. The introduction of the the phenomena of freezing and melting through experiments in Lessons 4 and 5 followed by animations that provide models for solids and liquids make this core idea clear to students. In addition, a model for molecular motion during a change of state is well illustrated.

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

Comments about Including the Disciplinary Core Idea
As post-lab activity after the experiments in Lessons 2 and 3 and before the students see the animation ask them to draw a diagram of the particles in the gas (and then the liquid in a separate drawing) are doing, Direct the students to pay attention to the distance between the particles and to indicate their motion.

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

Comments about Including the Disciplinary Core Idea
An animation/simulation is introduced in the lesson to explain the phenomena the students have observed in their experiment. The term or concept of a model is not introduced but the idea that the animation is only a representation of the real molecules should be pointed out The term is used throughout the chapter and an alternative (space filling) model of water is introduced giving a sense of what a model is. The idea of a model could be explicitly introduced at this point together with the advantages and limitations of this particular model. Add the term “model” to the language in Student Activity Sheets asking students to describe the model used to explain evaporation, condensation, melting, and freezing.

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
The lessons use simulation to explain the phenomena the students have encountered. With the focus on the molecular/atomic level simulations, the input to the system (temperature), the cause, is not identified explicitly and related to the effect. Lessons can be modified to include the crosscutting concept by referring to the cause and effect explicitly in the student worksheets and discussions.

Resource Quality

  • Alignment to the Dimensions of the NGSS: The lessons begin with a phenomena, invite students to design an experiment which allows them to create explanations using designated conceptual ideas. The rating would be superior if the practices and crosscutting concepts were more explicit.

  • Instructional Supports: Well developed lesson plans but no provisions for explicit integration or ELL. The investigations followed by the animations provide an excellent opportunity for language development on the part of all students but particularly ELL students. By organizing small group discussions of the experimental results ELL students can hear appropriate language and practice their language skills as they describe orally and in writing their observations. Use word wall to reinforce and practice new vocabulary in the lesson. The animations provide a similar opportunity for total class discussion. A potpourri of strategies linked to the science and engineering practices in NGSS are described in an article in The Science Teacher (Wong, S.S., Ortega, I. 2015. Dialogues for Success; Helping New Teachers of English Language Learners. The Science Teacher 82 (4): 51.

  • Monitoring Student Progress: There is no explicit provision for monitoring student progress but a number of questions are provided that can be used as formative evaluation throughout the lessons.

  • Quality of Technological Interactivity: Simple but easy to use animations that can be downloaded as CSV files for use independent of internet connectivity.