**Teacher Notes**

This resource is a compilation of text, videos, and other elements to create a scaffolded 5E learning experience for students. This is meant for Tier I instruction under the Response to Intervention (RtI) model for grades 10–12 and student expectation Chemistry (8)(D).

Be sure to review the entire resource and the related items before assigning it to, or working through it with, your students to check for prerequisite knowledge and skills as well as differentiation needs.

This resource can be used for instruction in a variety of ways.

• Use with a single computer and projector. (This can be delivered in a traditional classroom.)

• Use with a combination of teacher computer/projector and individual student computers (in a computer lab or other 1:1 environment).

• Assign to students as work to do outside of school as part of a flipped classroom to allow for application, practice, and additional support during the school day.

• Use with students as tutorials.

• Share with parents to inform them about what their child is learning in school.

• Use with students who are unable to participate in the traditional classroom environment.

**Engage**

The sandwich illustration and interactive activity are intended to give students a real-life example of balancing to which they can relate. The idea is for students to see that the number and types of ingredients do not change during the “reaction” of making sandwiches; they only rearrange. A common misconception is that atoms of one type of element change into a different element during a reaction rather than rearranging to form new or different molecules. It is common sense to students that cheese does not turn into bread, and therefore, the engage activity should lay the foundation for addressing this misconception. Students could be asked for other examples from everyday life in addition to the sandwich example in order to help them visualize this concept. Some ideas are making s'mores, building a bike, or making a car (using tires, a steering wheel, doors, and a frame).

**Explore 1**

The purpose of these video clips is to allow students to explore the concept of the law of conservation of mass and see what is happening in a sample reaction. They should notice from the mass shown on the balance that the mass did not change. The second clip is intended to begin to lay the foundation for addressing the concept that atoms do not change types but rearrange to form new or different molecules. This exploration could also be demonstrated or simulated in the classroom for kinesthetic learners who need to experience things in order to better interact with the concepts. The teacher could conduct a similar demo in person and have students discuss or write about their observations.

**Explain 1**

Students should gain an understanding of the law of conservation of mass and how to count atoms. It is vital that students master the concepts of subscripts and coefficients when counting atoms. They must be able to recognize if an equation is balanced or unbalanced before they can learn to complete the process of balancing for themselves. Another student misconception is that mass can be gained or lost during a chemical reaction. The section dealing with the masses of reactants and products is intended to address this misconception. Combining this information and the skill of counting atoms should help students bridge the gap from mass to atoms and see that both remain equal in a balanced chemical reaction.

**Explore 2**

Students are to experiment with balancing an equation through a simulation that allows them to see the atoms. This is helpful because it allows students to visualize what is taking place during a reaction. You do not want students to depend on a visual in order to balance equations, but it is key to helping them visualize the process. Because the simulation can be done by trial and error without understanding the process of balancing, it encourages students to explore the concept and make their own discoveries about how to balance if they do not remember this skill from middle school (8(5)(F)). In addition to the simulation, you also could demonstrate or act out the process of balancing using different colored circles of paper or balls to represent the different atoms.

**Explain 2**

The tutorial videos walk students through the process of balancing equations by showing an example and giving a step-by-step process. It is key that students master the steps in the process in order to be able to apply it to different equations. Once students have watched the video and have taken notes, they can attempt to practice the sample equations. A video explaining how to balance each of these equations is available in the related materials, and students should be encouraged to watch these videos in order to check their thought processes. It can also be beneficial to students to work through a few practice problems with a partner, particularly if a confident student is paired with a struggling student. One idea is to write an equation on a large piece of paper and have the students work out the balancing process on the poster. Each pair of students should have a different equation. When all groups have finished, students can do a gallery walk and check each other's work. If they find something they do not agree with on another group's poster, they can make the correction off to the side so that the owners of the poster can rethink their answer. It is strongly recommended that students be given more practice problems in order to fine tune their skills and until they reach mastery of this skill. The issue of balancing equations with the same element in more than one reactant or more than one product must also be addressed, as the total count of atoms must be done carefully. Finally, the Lavoisier video provides students with an understanding of the history behind the concept of the law of conservation of mass.

**Elaborate**

Students are challenged to look at balancing equations in everyday life and apply the law of conservation of mass to the example of photosynthesis. This allows students to see the importance of the concept outside the context of a chemistry lab or pharmaceutical company. They are also asked to present an explanation for a possible change to the equation and justify their thoughts. The questions encourage students to make predictions in terms of cause and effect. Upon completion of this section of the lesson, students would benefit from an opportunity to share their thoughts with others and discuss their ideas and rationale.