Changing State - Evaporation

Contributor
American Chemical Society (ACS)
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 lesson (2.2) is the second lesson in Chapter 2: Changes of State from Middle School Chemistry produced by ACS.

The lesson, which is outlined comprehensively in the lesson plan, follows the BSCS 5E Instructional Model. The “engage” phase begins with a series of questions as a way of helping students design an experiment to see if the the temperature of a small sample of water on a paper towel will affect the rate of evaporation. A well described experiment follows in the “explore” phase. In the “ Explain” phase a simulation that illustrates water molecules at different temperature and their effect on the rate of escaping the liquid phase is introduced to explain the observations in the experiment.

The particles of water are illustrated using both the ball and stick and the space-filling models.

The website includes downloadable pdf documents for the lesson plans, the entire chapter, student activity sheets, 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 lesson plan and simulation address the motion of molecules related to temperature for liquids and the effect on evaporation, a change of state. Temperature is the term used in the resource but it’s connection to thermal energy is not included. This could be pointed out if previous lessons have developed the idea of kinetic energy. Other lessons later in this chapter address other changes of state. This lesson should be considered as one lesson leading to a complete understanding of the outcome in the performance expectation. It develops the relationship between temperature and the motion of the particles/molecules in a liquid that produces evaporation. Ideally, it should be used after the lessons in Chapter One especially the lesson, Molecules in Motion. Subsequent lessons in the series develop the effect of temperature on the motion of particles of a gas and how reducing their motion results in condensation. Other lessons deal with freezing and melting. All of these lesson are needed to fully meet the performance expectation

Science and Engineering Practices

This resource appears to be designed to build towards this science and engineering practice, though the resource developer has not explicitly stated so.

Comments about Including the Science and Engineering Practice
Three different modes of the water molecule are 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. A description of a model could be introduced at this point together with the advantages (such as the ability to infer what is happening at the microscopic level of the particles/molecules of water) and limitations (such as the size and detailed structure of the particles is not included in the model) of this particular model. As a follow-up activity or a form of assessment, students could be asked to draw a model to describe the molecular level motion of the water during evaporation. Students could also be asked to use their styrofoam models of water molecules to explain what is happening to the molecules at an atomic level during evaporation

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
This lesson deals with the change of state of a liquid to gas during evaporation. Subsequent lessons in Chapter 2 of this series develop the effect of temperature on the motion of particles of a gas and how reducing their motion results in condensation. Other lessons deal with freezing and melting. All of these lesson are needed to fully meet this disciplinary core idea.

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

Comments about Including the Disciplinary Core Idea
Through the use of the experiment, discussion questions, and teacher explanations students should develop a good understanding of the core idea for water and gases. A more comprehensive approach to this idea that includes solids is developed in Chapter 1: Matter- Solids, Liquids and Gases, www.middleschoolchemistry.com/lessonplans/chapter1/lesson2 Idealy, this lesson should be used after the lessons in Chapter One especially the lesson, Molecules in Motion. Subsequent lessons in Chapter 2 of this series develop the effect of temperature on the motion of particles of a gas and how reducing their motion results in condensation. Other lessons deal with freezing and melting. All of these lesson are needed to fully meet this disciplinary core idea.

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 fact that the temperature change is causing the change in motion (effect) needs to be explicitly pointed out to the students. This language can easily be added to the lesson plan during the discussion of the simulation in the explanation phase.

Resource Quality

  • Alignment to the Dimensions of the NGSS: The explicit use of DCI is well addressed in the lesson. Students have an opportunity to make sense of phenomena by using a model is inherent in the use of the 5E model. The lesson highlights the relationship between temperature and the two changes of state through observing water as the temperature changes.The simulations and models help guide the learner to understand how molecules in gas, liquid and solid move relative to one another as the temperature changes.

  • Instructional Supports: The comprehensive and detailed lesson plans that follows the BSCS 5E instructional model provides excellent instructional support for the lesson as it is designed. It should be modified to have a more explicit conversation about the simulation as a model, and how the temperature and motion relationship is a idea of cause and effect relationship in the explanation phase of the lesson.

  • Monitoring Student Progress: The lessons do not provide an explicit method for monitoring student progress. However, a teacher could check in with a lab group as they are making observations and ask probing questions while they working through their analysis. Questions such as, “What do you observe?” and “How can the movement of the particles explain what you observe?” would be useful. There is a test bank of questions for the entire chapter of which this lesson is a part. A number of those questions are useful as a means to measure progress as students move through the lessons.

  • Quality of Technological Interactivity: Although very simple, the simulation is straightforward and easy to manipulate. This simulation can be downloaded as an SWF file to be used without an internet connection.