In this lesson students are introduced to the concept of Earth's atmosphere through a reading, and then taught more details about the kinetic molecular theory and gas behavior through notes, videos, demonstrations, and practice questions.
For this lesson there are several resources needed:
1. For popcorn reading I use a bouncy ball.
2. For the syringe activity I provide a large syringe (with no needle) for every 2-3 students.
3. For the diffusion demonstration I use two large graduated cylinders. One of them contains ice cold water while the other contains nearly boiling hot water. I also use food coloring.
To begin the unit I have students perform a reading about earth's atmosphere and answer several questions as they read.
I like to have my students practice reading out-loud so I use Popcorn reading as a strategy. (For details about how this works see my reflection on Popcorn Reading in my Ionic, Covalent, and Metallic Bonds Lesson).
I chose this reading because it gives the basics of the atmosphere in terms of its layers, the importance of the various gases, and how scientists can measure parts of the atmosphere.
Before we begin reading I have students take several moments to read over the questions on the back of the reading so that they will know what they are responsible for answering at the end of the reading.
I then begin reading the first paragraph and then pass the ball onto another student who continues to read.
When the class is done reading the article I give them about 5 minutes to answer the questions on their own. I then tell them that if they are stuck with any of the answers that they should get help from their table groups and I give them another 3 or so minutes.
Notice how in example #2 the student highlighted information as she read to help find the answers to the questions.
To get students to start to think about gases I have them do an activity using syringes and then I create an event and challenge them to create a model of the diffusion that occurred.
I first start with the syringe activity and show students the first slide of the lesson's PowerPoint and have them look at the top of their Demos Paper. I like this activity because it gets students thinking about how pressure is related to air.
I then have students begin to think about diffusion by having students come up with a model of the smell of a cut up lemon moves around the classroom. I show students the second slide of the PowerPoint and have them look at the bottom of the first page of their Demos Paper.
I instruct students to predict and model what happens when an lemon is cut open and give them some time to work. After students complete their models, I stand in the middle of the classroom to cut open a lemon, having told students to raise their hands when they first smell the lemon. (If I forget to bring a lemon I also use air freshener or you can even use spray cleaner.)
This is an example of one student's responses to the questions for the activities.
Once students have started to think about gasses and pressure through the syringe activity I then go into notes with students.
I begin this section of the lesson by introducing the Kinetic Molecular Theory in terms of gases' size, motion, and energy (slides 4-6).
I then introduce pressure and explain how there are many units to measure pressure (slides 7-8). I also have students practice converting between the different units (slides 9-12). Many students get confused with pressure conversions so I need to make sure to explain to them that all of the units on the table on slide 8 are equivalent to each other so can be set equal to each other in a conversion factor.
I also remind students about temperature (which we already learned about first semester) and how to convert between Celsius and Kelvin (slides 13-15).
This is a copy of one student's filled in notes for this section.
To break up the notes I stop students and have a second demonstration to engage students into the next portion of the lesson. This portion of the lesson is on slide 16 of the PowerPoint and students answer questions on the back of their Demos Paper.
The goal of this demonstration is for students to understand that substances will move slower when the temperature is cold, and faster when its hot.
This is a movie of how I do this demonstration in my class.
Here are two examples of students filled in demo papers with answers to this demonstration at the top of the second page.
In this section of the notes I explain to students the concepts of diffusion and effusion. These notes are found on slides 18 to 22 of the PowerPoint and students fill in the notes on the second page of their Notes Graphic Organizer.
I begin by explaining how for both effusion and diffusion that the size of gas particles and temperature effect how fast they move (slides 17-18). When going over slide 18 I give students the molar mass of the different molecules shows so they can see the relationship between relative speed and mass.
I then talk about effusion and stress how its the escape of gas. I use the example of a birthday balloon slowly deflating over time (slide 19).
I then go over diffusion and explain how is simply the movement of gas around a room similar to the example at the beginning of class with cutting open a lemon or the smell of air freshener around the room (slide 20).
I show students the movie Diffusion of Bromine Vapor and have them answer several questions (slide 20-21).
I like this video because it gives a visual to students of how gases move.
Finally I have students perform two practice questions (slide 22). Again, it is helpful to remind students of how to determine molar mass using their Periodic Tables.
This is a copy of one student's filled in notes with the example problems.
For the last section of this lesson I have student revisit their model of cutting open a lemon and then begin their homework.