Types of Reactions Concept Attainment (Day 2)

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Objective

TSWBAT identify five different types of chemical based on characteristics of reactants and products.

Big Idea

This lesson uses concept attainment as introduction to 5 basic types of chemical reactions.

NGSS Alignment

This is day 2 of students being introduced to the different types of chemical reactions.  Students took a quiz during the first half of class on day 1, so they were only introduced to one type of reaction (synthesis) and the principle of concept attainment.

This class period is 40 minutes which provides enough time to finish the rest of the Concept Attainment lesson.  Typically, this lesson will take more than one 50 minute period, so starting it on a quiz day (day1) is good way to space out this lesson

Performance Expectation (PE)/Disciplinary Core Idea (DCI)

This lesson is aligned with HS-PS1-7, the uses of mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction; and DCI-PS1.B, the fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.  Student are introduced in this lesson to 5 different chemical reactions (discussed in the explore section) that show that conservation of mass can happen in a variety of ways.

Science and Engineering Practices (SEP)

Students will engage in the SEP of Asking Questioning and Defining Problems during this lesson.  As students are learning the different types of reactions they will be required to ask questions and make observations which are used to determine patterns that occur in each type of reaction.

Crosscutting Concepts (XC)

During this lesson students will recognize that patterns occur in science.  Students are expected to see that patterns exist in each of the 5 types of reactions they and be able to recognize each reaction based on these patterns

 

Review

7 minutes

To start the period students take out the Concept Attainment Worksheet from the previous lesson and do a quick review of the synthesis reaction with the group of people at their table.  After a couple minutes I ask a couple of students to provide a summary of what attributes are characteristic of synthesis type reactions.

After a couple of summaries, I have the Classifying Chemical Reactions Powerpoint cued up and provide a quick review of slides 1-8 (synthesis reaction) from the previous day. I mostly do this refresh students with the process of asking themselves questions and writing down descriptions of positive attributes, not examples the reaction.  I spend 10 seconds on each slide, so we can move on to the 4 other reaction types.

 

Explore (day 2)

20 minutes

The first 10 minutes the remaining 4 reaction types will provided.

Implementing Concept Attainment Slides 9-32 (10 min)

  1. Explain the graphic organizer is used for writing down thoughts about positive (yes) attributes of each type of reaction.
  2. Showing an example of the next type of reaction, decomposition.  This is followed by one that is not an example.  Go slow in the beginning to allow for processing of information. 
  3. Let them know it may take several examples/non-examples before they start making a connection.
  4. As they make observations about characteristics or attributes of the type of reaction, instruct them to write them down.  It’s important to mention to the students the goal is not to write down examples, but instead use words to describe the positive attributes.  Again provide processing time.
  5. Repeat step 2 with the rest of the examples.  Providing process time in between
  6. Provide name of type of reaction
  7. Repeat steps 2-6 with single replacement, double replacement and combustion reactions.

 

(5 min)

Once everyone has processed the information, and developed a personal explanation of positive attributes for each reaction, I have them share their explanation with another person and fill out the second group graphic organizer.  By the end of the lesson most students have attained a good understanding of what pattern is present in each type action.  However, some student still have a difficult time articulating it in writing, so completing the graphic organizer with a partner can aid in the process of stating a pattern in words for each reaction type.

Class Sharing (5 min)

During this portion of the lesson students will be assigned to provide an explanation about a type of reaction.  The number of repeat reactions is dependent upon the number of groups.  If there is an uneven number of groups to provide equal number of examples for each reaction, additional group explanations will go towards double replacement, single replacement and combustion because these are the most difficult to for students to comprehend.

While groups are working on the GO, I assign each group a number (which is written on the board) and a reaction type.  After they complete the GO they are instructed to write their explanation on the board under their number.

After everyone has provided an example on the board, students are instructed to look at each explanation, compare it to their own and make any modifications.  At this point students can ask any questions they need addressed.  Typically there are none because they have enough time to develop a concrete explanation of attributes of each type of reaction.

 

Evaluate

15 minutes

As students are working on the group GO I hand out a bag with 10 different types of reactions written on strips of paper.  

Instruction

  • I explain the contents of each bag contains 10 strips of paper with chemical equations.  Each bag will have at least one of each reaction type (synthesis, decomposition, single replacement, double replacement and combustion) with some types being represented more than once. . 
  • Students first organize each reaction into groups based on reaction type.
  • Then they call me over to check for correctness.
  • If correct, write each reaction in the group GO under the appropriate reaction type

This part of the lesson is straightforward, requires little explanation and is successfully completed by students.  I don’t collect it or provide points because it is meant to be used as a comparison to their formal explanation that they will receive in the next class period.