Jennifer Smith MONTICELLO MIDDLE SCHOOL, MONTICELLO, IL
8th Grade Science : Unit #2 - Chemistry : Lesson #7

Reaction Rates - Flipped (Day 1)

Objective: SWBAT identify various factors that can increase and decrease a reaction rate and then manipulate those factors in the lab.
Standards: MS-PS1-2 MS-PS1-6 SP1 SP3 SP4 SP5 SP6 XC-P-MS-3
Subject(s): Science
60 minutes
1 Engage - 5 minutes

When the students enter the room, they take out their Chromebooks and log into Socrative to begin working on the journal prompt:  

What is a chemical reaction?  How can the rates of chemical reactions be controlled?  Provide examples.

I circulate through the room, looking at the students' responses to better guide class discussion. Once the students are finished, I show their answers on the screen anonymously and ask students to provide explanations as necessary.  

Generally, the students are able to describe observations that can be made when a chemical reaction takes place, meeting NGSS MS-PS1-2 and as reviewed during the physical and chemical changes lab conducted earlier in the unit.  They are also able to identify that temperature can be used to control reaction rates.  The students tend to respond with rote answers directly from their flipped notes, demonstrating that they have taken the notes and remember previous activities, but falling short of demonstrating a deeper understanding of the notes by using their own words to describe the manner in which reaction rates can be impacted. In these examples, several of the students include information about Collision Theory without explicitly stating the theory.  One student responds with a question about a reaction's relationship to balanced equations.

2 Explain - 15 minutes

Link

The students take out their flipped notes (taken from the video above while working at home) about reaction rates and we review them together in class.  At this point in the school year, I am moving toward having the students begin leading the review of the notes.  To do this, I ask for volunteers to explain the notes on the screen or to provide additional examples.  I redirect the students as necessary and facilitate the discussion by asking clarifying questions such as, "What do you mean by...?" and "Can you provide examples?" I also emphasize endothermic and exothermic reactions and refer back to the balloon reaction from the physical and chemical changes lab (NGSS MS-PS1-6).

Importance of Word Choice
Coherence

Word choice is vital in explaining the concept of reaction rates.  For instance, I used the word speed in the flipped notes, so during the class discussion, I pointed out that in this instance I used the term speed to mean how quickly the reaction took place.  Some students also showed confusion with the terms dealing with increasing and decreasing the rate of reactions.  Some of the students incorrectly thought that decreasing the temperature would decrease the rate of the reaction causing it to happen more quickly instead of more slowly.  In these instances, it was helpful to discuss molecular motion at different temperatures -- a reminder that molecules move more quickly at higher temperatures and more slowly at lower temperatures. 

3 Explore - 15 minutes

After reviewing the notes, we move into the science laboratory.  It is important to review key portions of the lab first. This helps to stress that labs are more than "doing things". These are purposeful and thoughtful activities. So, we begin the process by developing an operational definition to decide when a reaction rate is complete.  Next, a control is developed as I provide a brief demonstration of reaction rates by dropping Alka Seltzer into tap water.  I time the reaction and write the time on the board.  This is done twice, once while stirring and once without stirring. 

I ask the students to discuss both qualitative and quantitative observations before, during, and after the reaction.  I then refer the students back to their lab sheets and review the guidelines for the lab activity. I ask the students to use their information from the flipped notes to develop an investigation in which they speed up or slow down the rate of the reaction (CCC Patterns - Patterns can be used to identify cause and effect relationships).  The students work in groups of four to develop a hypothesis and then develop independent and dependent variables (SP3 - Planning and Carrying Out Investigations).  I encourage the students to look through the materials available to them at their lab tables and to read through the sample materials and procedures list in the laboratory instructions (SP1 - Asking Questions and Defining Problems).  

4 Wrap up - 5 minutes

The lesson concludes with a whole group discussion about the investigations developed by the students.  The students speak with the other partner group at their table to share ideas.  Once they have had a chance to discuss, the groups are invited to share their information with the class.  The other students are encouraged to ask questions about the investigations as well.