Specific Heat

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Objective

SWBAT define specific heat and identify how specific heat affects the heating and cooling rates of land and water surfaces

Big Idea

Students learn about specific heat, how to define or measure it, and sequence the specific heats of various substances

Lesson Introduction

In this lesson, students learn about a fundamental and basic component of Earth's systems, and one that accounts for so many phenomena on Earth's surface and in the atmosphere - specific heat! We start the lesson by first introducing and defining what it is, specifically from an energy use point of view. We then transition into a mini-lab which quite literally demonstrates the process of how water, due to its high specific heat, will not change temperature as easily as other surfaces, due to its inherently high specific heat. Students see this for themselves and then graph the associated information. The second part of this lesson does require materials, which are listed below:

Materials: (These will make one setup. You should ideally have one setup for each laboratory group)

[Note: For embedded comments, checks for understanding (CFUs), and key additional information on transitions and key parts of the lesson not necessarily included in the below narrative, please go to the comments in the following document: 6.3 - Specific Heat (Whole Lesson w/comments). Additionally, if you would like all of the resources together in a PDF document, that can be accessed as a complete resource here: 6.3 - Specific Heat (Whole Lesson)[PDF]. Finally, students may need their Earth Science Reference Tables [ESRT] for parts of the lesson (a document used widely in the New York State Earth Science Regents course) as well.]

Do Now

10 minutes

Students come in silently and complete the (attached) Do Now. In this case, the Do Now is a review of material and some "hot standards" from earlier units in addition to some needed review on material from the current unit on Climate. After time expires (anywhere from 2-4 minutes depending on the type of Do Now and number of questions), we collectively go over the responses (usually involving a series of cold calls and/or volunteers), before I call on a student and ask them to read the objective out loud to start the lesson.

As a general note, the Do Now serves a few purposes:

  1. It serves as a general review of the previous day's material;
  2. It is a re-activation of student knowledge to get them back into "student mode" and get them thinking about science after transitioning from another content area or alternate class;
  3. As a strategy for reviewing material students have struggled with (for example, using this as a focused review for material that they have struggled with on unit assessments or recent quizzes); and,

It is an efficient and established routine for entering the classroom that is repeated each day with fidelity (I never let students enter the classroom talking. While it may seem potentially severe to have students enter silently each day, this is both a school wide expectation and a key component of my classroom. In many respects, I find that students readily enjoy the focus that starting with a quiet classrooms brings each day).

Specific Heat Introduction

15 minutes

We start this lesson with a quick hook (attached here as the Specific Heat Hook). It contains one image, which is a picture of my favorite candy - Reese's Peanut Butter Cups (unbelievably delicious). Before I show the image, however, I ask the class what my favorite candy is. Eventually, someone is usually able to get to the correct answer, after which I display it on the board. 

I then ask students: "How would I determine how much energy is in this candy?" Students are usually quick to point to the nutritional information on the package, which lits the calories that the candy contains. I then use this to transition into the Specific Heat Introduction, where I indicate that we're going to get the "official scientific" definition of what a calorie is.

Looking at the first page of the Specific Heat Introduction, we read the top paragraph together before students are asked to answer the Quick Check question on how a calorie is defined. After reviewing the answer, I then ask students to reference the first page of their Earth Science Reference Tables [ESRT], which contains information on the specific heat of various substances. 

We then continue to read as a class, after which I ask students a series of basic questions about the specific heat of the listed substances on their Earth Science Reference Tables [ESRT], such as "Which has the lowest specific heat?" or "Which substance has the highest specific heat?" After reviewing this information and continuing to collectively read the final two paragraphs, we transition to the Notes section, which is on the second page of the Specific Heat Introduction resource. 

The Notes section contains the basic facts that students need to take away from the lesson - objects with a high specific heat both heat up and cool down at a much slower rate than those with a lower specific heat. That one fact can more or less carry students to correctly answer any Regents-based question or specific heat related information contained in this Regents course. Before jumping into the next section, I have students work on those final Review questions as an opportunity to cement their understanding of the key ideas and facts of the lesson. 

Mini-Lab

25 minutes

After completing the basic information about specific heat, we transition into a short, 25-minute laboratory exercise that demonstrates the concept of specific heat for students (Note: There was a materials issue with this lesson, and I had to conduct it as a demo instead of a student-centered laboratory exercise. Normally, there would be enough materials for each student lab group of four to conduct the experiment. The video and lesson here are presented as I did them, but it can easily be accommodated as a lab, which is how I usually conduct it).

As with all labs, you should accommodate enough time for setup and to ensure that all parts (especially the infrared lamps) are working appropriately. As noted above, I did this as a demonstration at the front of the room with just one setup, but you should allot for extra time and/or helpers to distribute all the necessary materials quickly and easily (I usually pre-assemble everything into kits that can be easily passed back, and they make for quick and easy cleanup). 

The concept of the lab is relatively straightforward. In essence, two thermometers are placed in two different cups, each filled with an equal volume of soil and water, respectively. An infrared lamp is turned on and the temperature is taken once (in degrees Celsius) every sixty seconds. This is done consecutively for nine (9) minutes, after which the lamp is turned off, and the temperature is then taken once a minute for an additional 9 minutes. The data, which has been recorded on the associated data table on the Graph Data & Discussion Questions (Student Copy). Students then use the graph paper contained in the Graph Data & Discussion Questions (Student Copy) to create a double-line graph of both the soil and water (students will have to label the axes and interval/scale for both). The discussion questions follow directly in the Graph Data & Discussion Questions (Student Copy). As a note, there is sample data and a completed computer-generated graph contained in the Graph Data & Discussion (Teacher Sample) to give you an idea of how the lines and data might look (the water will not change much, and that's okay!). 

Your role as the teacher will change depending on it being a demo or lab, but as I did this as a demonstration, I encouraged students to graph simultaneously in the 60-second intervals when they were waiting for data. If you're conducting this as a lab, I would focus most of my observational energy on making sure that students complete the graph with full fidelity. As this is something that's reasonably well practiced at this stage, mistakes, especially with the scale & intervals in some of your struggling graphers might still appear. You can also encourage students to cross-check their work with their peers as well in an effort to minimize mistakes. 

Exit Ticket

5 minutes

In the last few minutes of class, I have students complete the daily Exit Ticket. For the sake of time, I have students grade them communally, with a key emphasis on particular questions and items that hit on the key ideas of the lesson (Note: This usually manifests as students self-grading, or having students do a "trade and grade" with their table partners). After students grade their exit tickets, they usually pass them in (so that I can analyze them) and track their exit ticket scores on a unit Exit Ticket Tracker. 

After students take a few seconds to track their scores, we usually wrap up in a similar way. I give students time to pack up their belongings, and I end the class at the objective, which is posted on the whiteboard, and ask students two questions:

  • Do you feel that you mastered the objective for the day?
  • Can you reiterate one thing you learned about (in this case, information on specific heat and substances that have particularly high/low specific heats, etc.)?

Once I take 2-3 individual responses (sometimes I'll ask for a binary "thumbs up/thumbs down" or something similar), I have students leave once the bell rings.