In this lesson students are introduced to the concepts of temperature, heat, exothermic reactions, and endothermic reactions. This is done through notes, lab activities, a model, and a computer activity.
For this lesson students need several resources:
In this first section of the lesson I give students a chance to think about what we will be learning during the lesson and get at their prior knowledge concerning temperature and heat.
I then read the scenario about the temperature of four different objects after sitting out in the classroom overnight. After reading the scenario I also show them examples of similar objects in my classroom (a block of wood, a sheet of metal, a ball of wool, and a square of glass).
I instruct students to think about the scenario and choose the answer that they think is best. I also tell them to try to describe WHY they think that their choice is the best. Finally I tell students that if they are not sure to still come up with an educated guess based on their prior knowledge.
As students work I walk around the classroom. When the majority of students seem to have chosen an answer and wrote out WHY they chose that answer (usually about 5 minutes) I instruct students to share with their table partners.
I then take a poll of the class for each answer. I do this by saying "Okay, we are going to see what we think is the best answer. Raise your hands if you felt that A was the best answer." I then wait for students to raise their hands and then go onto B through D.
Finally I show slide 3 of the PowerPoint and go over the answer of "D" and explain why it is correct in terms of ambient temperature and they should have the same average kinetic energy. I tell them that I understand it is tricky with how the object "feel" with some feeling cold and some feeling hot, but that we will explore that idea more within this unit when we discuss specific heat capacity.
This movie shows how I review the answers in my classroom.
For the next section of the lesson I have students begin to think about what happens when hot and cold substances are placed together. To do this I have them do two things:
First, I have students perform a quick lab so that they have a chance to visualize what happens when they mix hot and cold water together.
Second, I have students draw a model of what happens when they mix equal amounts of 0 degree and 100 degree water together.
For this next section of the lesson I present notes to students regarding heat and the different measurements for heat. These notes are found on slides 6 and 7 of the PowerPoint and students fill in their notes on the bottom of their notes graphic organizer.
While I teach students the various terms and equivalence statements I point out that they are located on the word wall at the back of the classroom. Here is a picture of the word wall.
Here is a copy of a student's filled in notes for this section.
In this section of the notes students have a chance to practice some energy conversions with two examples.
Because students have done lots of dimensional analysis they find these problems pretty easy. I make sure to reiterate that they should underline what they know, circle what they want, and then set up the problem to convert the given to wanted.
This movie shows how I help students to solve problem #2.
Here is a copy of a filled in graphic organizer.
In this next session of the lesson I introduce the concepts of temperature and heat on slides 12 and 13 of the PowerPoint. Students fill in their notes on the second page of their notes graphic organizer. When I talk about heat I show students a second Heat flow PowerPoint which shows how energy is transferred between two boxes (one hot and one cold).
This second PowerPoint shows what happens at the molecular and macroscopic levels. I have students perform a model of the reaction which I help them to complete by demonstrating what they should have on the board.
Here is a copy of a student's filled in notes. Notice how on the second page their model shows what happens at the particle and macroscopic levels and also shows why this occurs.
In this section of the lesson students have another opportunity to work with energy changes in a PhET activity.
In this final section of the notes I explain to students the concepts of thermochemistry, how energy changes in chemical reactions, and the difference between exothermic and endothermic reactions.
While I explain the notes to students I present many examples to help them understand the concepts.
Here is a copy of the filled in notes.
In this part of the lesson students perform another quick lab to check their understanding of chemical reactions and the difference between endothermic and exothermic reactions.
The final section of this lesson is students' homework. The homework is found on the last page (page 4) of the student notes graphic organizer.
The homework gives me a chance to test students understanding of the lesson. There are questions related to various parts of the lesson.
I have students complete the homework and stamp for completion the next day. I review the answers using the practice key
The problems that students find the most difficult include:
#3 Where they are finding food Calories as Kilocalories (Cal). Some students get confused with converting between calories and Kilocalories (Cal).
#4 With some students not showing WHY they become the same temperature and other student not showing what happens at the particle level.
#5 Some students aren't sure how to describe the difference so I make sure to tell them to use the definitions to help differentiate.