Day 2- Physical vs Chemical Changes

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SWBAT write evidence based explanations to distinguish physical and chemical changes.

Big Idea

Students will construct scientific explanations that demonstrate their understanding of physical and chemical changes.

Lesson Overview

5e Lesson Plan Model

Many of my science lessons are based upon and taught using the 5E lesson plan model: Engage, Explore, Explain, Elaborate, and Evaluate. This lesson plan model allows me to incorporate a variety of learning opportunities and strategies for students.  With multiple learning experiences, students can gain new ideas, demonstrate thinking, draw conclusions, develop critical thinking skills, and interact with peers through discussions and hands-on activities.  With each stage in this lesson model, I select strategies that will serve students best for the concepts and content being delivered to them.  These strategies were selected for this lesson to facilitate peer discussions, participation in a group activity, reflective learning practices, and accountability for learning.

Unit Focus  

The Matter and Energy unit focuses matter: anything that takes up space, has mass, and can neither be created nor destroyed, only changed.  To help students develop their understanding on these concepts, they take part in a variety of guided inquiries geared towards scaffolding this understanding.  This unit begins by defining matter and its properties. Students apply these properties throughout the unit as they explore how matter changes forms, how the effects of temperature on solids, liquids, and gases, and how a mixture and solution differ. They need to develop an understanding these forms of matter for as the second half of the unit which focuses on physical and chemical changes of objects and substances, reactions, and energy.

Lesson Synopsis

This is the second day of the Physical vs Chemical Changes lesson. In the first part of this lesson, students participated in stations to investigate and distinguish physical changes from chemical changes. Today, they engage in arguments using evidence from their investigation to conclude what type of change took place at each station.  By the end of the lesson, students use their vocabulary foldable from yesterday, and information learned today as their evidence to construct a claims and evidence based explanation. This is collected as an assessment on their understanding of physical changes vs chemical changes.

Next Generation Science Standards  

This lesson will address the following NGSS Standard(s): 

5-PS1-3. Make observations and measurements to identify materials based on their properties.

5-PS1-4. Conduct an investigation to determine whether the mixing of two or more substances results in new substances

Why Do I Teach this Lesson?

I created the day 2-Physical vs Chemical Changes lesson with a focus on the science and engineering practice 7:  engaging in argument from evidence. Many of my students have very limited background in science since the elementary school's within my district do not formally teach science prior to my students entering the 5th grade (the middle school). I find it important to expose my students to how scientists investigate questions or ideas and apply their evidence to explain outcomes and phenomenons. Furthermore, providing my students the opportunity to practice this type of discourse will help to facilitate their scientific thinking for future investigations in any lesson.

Scientific & Engineering Practices

Students are engaged in the following scientific and engineering Practices

7.) Engaging in Argument from Evidence:  Students use their investigation observations from yesterday to construct an argument with a claim, evidence, and scientific reasoning. They respectfully engage in discourse with a peer as one claims it is a physical change and the other claims it is a chemical change. They listen, compare, and evaluate others' ideas throughout the process.

8.) Obtaining, evaluating, and communicating information: Students use evidence from yesterday's investigation and vocabulary foldable to write a scientific explanation on what type of change occurred during the investigation. 

Crosscutting Concepts

The day 2-Physical vs Chemical Changes lesson will correlate to other interdisciplinary areas.  These Crosscutting Concepts include:

2.) Cause and Effect:  Students use evidence and scientific reasoning to explain if the object when through a chemical or physical change.

6.) Structure and Function: Students identifies and describes the changes each material used in yesterday's investigation occurred. They describe how the structure of each item either physically or chemically changed and if these changes affect their function and purpose.

Disciplinary Core Ideas

Disciplinary Core Ideas within this lesson include:

PS1.A Structure of Matter:  Measurements of variety of observable properties can be used to identify particular materials. (Because matter exists as particles that are too small to see, matter is always conserved even if it seems to disappear.) 

PS1.B Chemical Reactions Chemical reactions that occur when substances are mixed can be identified by the emergence of substances with different properties; the total mass remains the same


Importance of Modeling to Develop Student

Responsibility, Accountability, and Independence 

Depending upon the time of year, this lesson is taught, teachers should consider modeling how groups should work together; establish group norms for activities, class discussions, and partner talks.  In addition, it is important to model think aloud strategies.  This sets up students to be more expressive and develop thinking skills during an activity.  The first half of the year, I model what group work and/or talks “look like and sound like.”  I intervene the moment students are off task with reminders and redirecting.  By the second and last half of the year, I am able to ask students, “Who can give of three reminders for group activities to be successful?” Who can tell us two reminders for partner talks?”  Students take responsibility for becoming successful learners.  Again before teaching this lesson, consider the time of year, it may be necessary to do a lot of front loading to get students to eventually become more independent and transition through the lessons in a timely manner.




25 minutes

Guided Discussion Using Evidence 

I start off asking my students to re-examine their investigations and re-look at the conclusion they made for each one.  Did you think ____ (item tested) was a physical change or chemical change?  

conclusion statement    conclusion statement


I have my students use their chemical change / physical change foldable to help them identify the kind of change they observed and to write a claim with evidence and reasoning.

At this point, I explain to students that they are pairing up to engage in a friendly argument about the conclusion they made about each investigation.  I tell them they are stating their claim (chemical change or physical change) to their partner and providing evidence to support their claim from their investigation and the information in their foldable about each kind of evidence.

Before I have them begin, I select a pair of students to use a model while I coach them. I find my students need a model of the expectation for this kind of academic discourse. One student states her claim about the change in the item while the other one listens. After she finishes stating her claim, I say "If you disagree, use the sentence starter, I respectfully disagree with_____.  I believe the _______ is a __________change."  I continue coaching her by asking her to follow up with evidence and reasons from her investigation, foldable, and past activities.  I remind her and the class it must be factual, not opinion based. I ask other students to jump in along the way to help the flow of the conversation.  

Engaging in Argument from Evidence

After modeling the expectation, I name one investigation, ask students who claimed the change was physical to stand at one side of the room and the those who selected a chemical change at the other side.  I quickly pair up students, remind them of the expectation for the conversation, and tell them to begin. 

While students converse, I circulate the room, listening to students provide evidence and reasons for their claims. I encourage them to ask questions about what they hear from their partner and to go back to their foldable to provide scientific reasoning evidence to support their thinking.  

I notice some groups need coaching along the way with this kind of discourse.  For some, I have to remind them to use the characteristics of each change to support their thinking. The experience reminds me my students still need practice in arguing with evidence.

 So What kind of Change Really Happened ?

I reconvene the class to identify and discuss the changes at each station. I ask them to keep their vocabulary foldable out. I want them use it as a reference throughout our discussion.

I project a powerpoint that names the station and evidence from each change that took place.  I call on a volunteer to share the type of change they claimed happened.  We go through each station, share observations, identify characteristics to help us determine what type of change took place.  I reveal the type of change that happened and provide scientific reasoning to explain why it was that kind of change.  I keep it simple with terms they are familiar with like substances, molecules, particles.  I want them to focus on understanding the properties of physical change vs. chemical change.


30 minutes

I handout a claims and evidence template and point out each section to the students: claim, evidence, and reasoning.  I explain they are organizing their claims, evidence and reasoning on here.  I remind them a good scientific explanation incorporates evidence and reasons support their thinking and help them write a well-written explanation.  

I direct my students to begin writing their claim statement.  Then I tell them to continue by adding evidence from their investigation station to support their claim.  Next they move onto thinking of the scientific reasons we discussed as a class when I went through the powerpoint and add them to further explain the change that occurred.

Students work on these for the remainder of the time. While they work, I move around the room monitoring their progress.  


5 minutes

Before ending class, I ask students to fill out an exit ticket.  As I hand them out, I explain the task is to look at each picture in the process column on the left and decide if it is a chemical change or physical change.  Then mark an x the chemical change box or physical change box that they believe the picture is showing. 

I continue by directing them to the bottom half of the ticket where they are answering the two questions:

1.)  Can you describe what happens in a physical change?

2.)  Can you describe what happens in a chemical change?

I use this exit ticket to monitor student progress and as a formative assessment.  It provides me with feedback on students’ learning experience and understanding of chemical and physical changes. In addition, it identifies areas students are struggling with and/ or misconceptions they still have about these two types of changes.  

I tell the students to place the exit ticket in the bucket on the way out to their next class.