# Bohr and Balance - a Review

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## Objective

SWBAT independently complete Bohr models and balance increasingly difficult equations.

#### Big Idea

This lesson provides students with the opportunity to receive guided instruction and work independently on balancing equations and drawing Bohr models.

## Engage

5 minutes

As the students enter the room, they take out their Chromebooks and log into Socrative to answer a survey regarding their comfort level with balancing equations and drawing Bohr models.  Using Socrative allows me to view the student answers in real time and provides me with information about how to best lead the review for the day.  In this video, I explain how I use the results to guide my instruction.

## Explain

10 minutes

After viewing the students' answers to the survey, I lead a review of balancing equations and drawing Bohr diagrams.  I begin by reviewing how to balance Bohr diagrams.  For this review, I work a question on the board following only student prompts.  This helps the students become more responsible for the review and helps them work together to increase their understanding of the topic.

For instance, I begin by asking the students to select an element from the periodic table.  I then ask one student which part of the periodic table I should examine to find the number of electrons in an atom.  From there, I ask different students to instruct me on how to draw the Bohr diagram.  I only call on each student one time, which requires all students to participate.  After drawing a few Bohr diagrams, we move on to balancing equations.  I begin by writing an equation on the board and then having individual students explain a step of the process.  Again, I am careful to call on each student only once.

Working on Bohr models helps to meet NGSS SP2 by having students create models to represent various elements.  Balancing equations meets NGSS MS-PS1-5 because balanced equations are a representation of the Law of Conservation of Mass.  This lesson also meets CCSS Math EE.A.1 as students work with coefficients in order to balance equations.

## Explore

20 minutes

This portion of the lesson requires students to determine the area in which they are having the most difficulty and then to practice that skill.  Students who are comfortable with the material are asked to work on a website with increasingly difficult equations to balance.  Students who are not comfortable with one or more of the skills are asked to take out their notes for the specific item causing them difficulty and begin practicing the skill. During this time, I circulate among the students helping them individually or in small groups as necessary.  As students become more secure with balancing equations, they move to working on balancing equations using online resources.  Students practicing Bohr models are encouraged to have a neighbor check their work while they are waiting for me to get to them.

## Wrap up

5 minutes

Near the end of the hour, I call the students back together and we spend a little more time practicing as a whole group.  I write equations on the board and each student has time to work the equation on their own before we complete it together as a class.  I alternate between balancing an equation and drawing a Bohr model.  At this point, most of the students are completing both the equations and the Bohr diagrams with 100% accuracy.  A few students are still having difficulty, so I encourage all of the students to ask for help during study hall and I schedule a lunch study session for early the next week, so students can come into my classroom during lunch to receive help and practice.