In this lesson I introduce students to temperature scales and unit conversions using equations.
Most students come into my class having used Celsius and Fahrenheit scales in previous science classes and about half of them have learned how to convert between the two scales. My goal is to build on this knowledge, introduce the Kelvin scale, and help them convert between the scales using my "plug and chug technique" of underlining what they know, circling what they, figuring out what equation to use, and then plunging and chugging to get an answer.
This lesson aligns with Science and Engineering Practice 5 "Using Mathematics and Computational Thinking" because students are learning to solve problems using temperature conversion equations.
Finally, the reading at the end of the lesson gives students a chance to work on their literacy skills through reading an analytical text.
For the activity in this lesson I use one beaker of ice water, one beaker of room temperature water, and one thermometer or temperature probe per group.
To begin the lesson I ask students to reflect on the question, "What are some values for temperature?" After a few seconds of wait time I ask for volunteers to share out. I get responses related to measuring the temperature of your body (like 98.6 degrees Fahrenheit) and the temperature of the classroom. From these responses I highlight students' use of various units which usually include Celsius and Fahrenheit, and sometimes Kelvin.
In this section students take notes to learn about temperature and temperature conversions using the lecture 4 graphic organizer while I present unit1 lec4 PowerPoint. This is a lesson where some students are familiar with some of the content, but I find it very helpful to take the time to make sure that all students understand the different scales as well as begin to see how to problem solve in chemistry.
These are relatively short set of notes that is mostly filled with practice questions where I help students learn how to plug and chug with equations. I explain in more detail how I do this in the "problem solving in chemistry" reflection. The answers to the three practice questions at the end of the PowerPoint are here.
Also while students are writing their notes I have them watch two videos. One is from youtube about absolute zero:
The other video is about Charles Law as a way for scientists to determine the value of absolute zero. I find these helpful for students to better get a grasp on this idea of "lowest possible temperature". When students are done with watching the two videos I have them fill in the box on their notes concerning how absolute zero was discovered. I emphasize how using Charles' law when volume reaches 0, then temperature would be -273 degrees Celsius which is absolute zero. Therefore students can see how absolute zero would be zero volume and no molecular motion.
Even though students may have done temperature conversions before it is really important to start to emphasize that in chemistry there are LOTS of equations and that they need to always follow the steps of underlining what they know, circling what they want, figuring out the equation, and then plug and chug to get an answer. This video from class demonstrates how I introduce this to students within the notes.
After taking notes I find it helpful to have students get out of their seats and do a quick lab activity. This is found on the back of their student notes.
I have my students use Vernier Logger equipment throughout the school year so use this as a time to introduce them to using the equipment (see probeware reflection for more details on how I use probeware in my classroom). I lead students through how to login to the computers and open the Go Lite software package. The students take two measurements using the temperature probes including one sample of room temperature water in a beaker and another sample of ice water in a beaker. I then have students perform simple calculations using the recorded values. This picture is an example of student responses from the activity.
Although this is a fairly simple activity many students notice that the temperature does not stabilize for the ice water. As I walk around to each group I lead them through the idea that as the water sits on the table that it is going to increase its temperature because of the warm air.
Within my classroom I have built up a set of Vernier Probeware over the years which I have found very helpful for students to be able to gather data that increases the "real-world" nature of labs, the rigor of labs, and student enjoyment. The probes I use include temperature, pH, gas pressure, dissolved oxygen, CO2, O2, barometer, conductivity, voltage, and colorimeter.
The probeware increases the real-world nature of labs because this is more closely aligned with how scientists gather data and how students will be gathering data in college.
The rigor of the classroom is increased because students are asked to perform higher level data collection and analysis using the software. Also, technology is a component that is part of the science and engineering practices that students should be able to use in the science classroom.
Finally, student enjoyment is increased because they enjoy working with computers, and having data in multiple formats (table and graph) helps students to better visualize the phenomenon at hand.
If you are interested in reading more about the merits or probeware the vernier_whitepaper goes over data as to why it is important to use in a classroom.
There are multiple types of probes, but I would definitely look into ordering some if your school/department has funds, or otherwise to apply for a grant to buy some. They are available through Vernier's website as well as other places such as Flinn scientific.
In this last part of the lesson I have students take some time to read about temperature.
I have two different articles that I have used in the past, but this year I only had students read and article about thermometers from a ChemMatters magazine article. Chem Matters is a magazine produced from the American Chemical Society and is available online. This article is a bit long but is nice because it goes into the definition of temperature, temperature scales, and types of thermometers. The second article which I sometimes have students read is from Smithsonian and discusses absolute zero.
One of my favorite strategies for reading in class is to have a ball that students pass around to take turns reading. This way they all have a chance to read a bit, but that they can also decide how much they want to read (from a sentence to a paragraph) before they pass the ball along. This gives them a chance to work on reading fluency.
When students are done reading I have them write down the three most interesting things that they learned while reading. They can do this on post-its, on a paper, or on whiteboards. They then discuss with their groups and then as a group come up with one or two items to share with the class. I then have each group share out what they found to be the most interesting thing that they learned while reading. These pictures show examples of student whiteboard responses of the most important ideas (student-ex1 student-ex2) in the readings and then one or two big ideas as a group (group-ex1 , group-ex2).
To evaluate students' learning I have them practice temperature conversions for homework which is at the bottom of the student notes. When students come in the next day I stamp their papers and review the answers with them using the answer key.
At the end of class, I give students a mid-unit quiz. The quiz is a review of concepts from the first 4 lessons in the unit.
The quiz takes most students less than 10 minutes to complete. When they are done with their quizzes I collect and grade using my answer key.
I then return the quizzes the next class period and have students make corrections on their quizzes and write their percentage that they earned (see Quiz Corrections reflection for more details about how and why I do this).
The most common quiz mistakes are dealing with dependent variable, rounding correctly with significant figures, and using an incorrect sign for exponents in scientific notation.
I have students perform corrections to make sure that they look over their mistakes. By doing this they can see what they did wrong, and are forced to figure out how to answer the questions correctly to help with mastery of content.
I also have students write their percentage because I have found that many of my students struggle with this basic skill and benefit from the practice.
Students are held accountable for quiz corrections at the end of the unit when I collect their binders to grade.