Supported by:
th
Standards:
8.3.8—Explain that all matter is made up of atoms which are far too small to see directly through an optical microscope. Understand that the atoms of any element are similar but are different from atoms of other elements. Further understand that atoms may stick together in well defined molecules or may be packed together in large arrays. Also understand that different arrangements of atoms into groups comprise all substances.
8.3.12—Explain that no matter how substances within a closed system interact with one another, or how they combine or break apart, the total mass of the system remains the same. Understand that the atomic theory explains the conservation of matter: if the number of atoms stays the same no matter how they are rearranged, then their total mass stays the same.
Objectives: In this lesson, students will be able…

Describe what is needed to have a balanced equation.

Balance a three element reaction.
Required material: 12 bolts, 12 nuts and 12 washers (for each group), pan balance (1 per group), instruction/lab sheet, (excel spreadsheet has copies of tables used in worksheet for easier teacher modification)
Lesson Introduction: In this lesson, students are given the opportunity to explore the concept of balanced equations by first doing a hands-on activity where bolts, nuts, and washers are used to develop the idea. The students will develop the balanced equations idea based on their inquiry work trying to get a pan balance to level out.
Procedures:
Day 1:
1.
Lay out materials so that each group has enough supplies.
2.
Organize students into groups of two-four. Hand out one instruction sheet per group.
3.
Advise student about how much time they have to accomplish the tasks and then tell them to get started.
4.
Circulate and observe student work. Make corrections to behavioral situations, but do not make suggestions about procedure or materials.
5.
Once everyone is finished or time is over, have students clean up materials and turn in worksheet.

6.
Review worksheets for correctness and accuracy.
Day 2:
1.
Have the students get back into their lab groups from yesterday.
2.
Hand back the groups worksheets and instruct them to each get out a sheet of paper.
3.
Have them put a heading on the paper.
4.
Tell them to answer the following questions on their paper and that they can talk about the answers with their group members.
5.
Question 1: Yesterday you used bolts, washers, and nuts on a balance. What were the restrictions that you were given?
6.
Circulate and watch groups interact and student participation.
7.
Question 2: Define what a group is for this activity?
8.
Circulate, watch and help as needed.
9.
Question 3: What did you have to do to get the balance to be balanced?
10.
Circulate, watch and help as needed.
11.
Have several students share their answers.
12.
Show the students a chemical equation (such as CaCO
3
 CaO + CO
2
) and have them write it on their sheet.
13.
Question: Could there be similarities between the reaction and the activity we did yesterday? How? Have students offer ideas about similarity.
14.
Label each compound as a group, and then define the word compound.
15.
Explain that each side of the arrow is like each pan of the balance. Explain which sides are associated with reactants and products.
16.
Compare and contrast the process of balancing equations to that of balancing the balance.
17.
Explain that we have to balance reactions because when a reaction occurs, none of the atoms (parts) of the compounds (groups) can be lost.
Appropriate Worksheets:
A worksheet for the students appears on the last two pages of this lesson plan. An excel document with the same name contains the tables so that they may be easily modified and then cut and pasted into this document.
Closure: Continue teaching about balancing reactions using notes, demonstrations, and worksheets.
Assessment: The teacher will…
1.
Observe students group participation and contribution.
2.
Indicate group success by initialing worksheets.
3.
Grade worksheets after students are complete.
4.
Use appropriate measures for analyzing students understanding of balancing equations.
Extensions: For a challenge, adding a fourth or five items to be part of the groups can be done.
It is suggested, to simplify preparation, that the teacher has a specific reaction in mind before trying to create a scenario.
Written by: Dustan Smith and Aaron Debbink, PIE Fellows, Ball State University

Balancing with Bolts
Names: __________________________________
Student worksheet
Your Task: Complete the four situations below and have your teacher check off each time you complete them.
___________________________________
Instructions:
1.
Below you will find four situations where you will have to cause a pan balance to become exactly balanced, using only the bolts, washers, and nuts given to you.
2.
Each situation has special pairing of these parts which must always be followed. a.
For example, in situation one, two nuts will be in a group in the left pan.
Therefore, you may only add nuts to the left side of the balance in pairs.
3.
When you have the balance balanced, fill in the answer tables showing how many of each group and how many of each part there are in each pan. Then raise your hand and if you have completed the situation correctly, your teacher will sign off on the completed situation.
4.
Once you have completed and have been signed off on all four situations, turn your group worksheet in for full credit.
Left Pan Right Pan
The groups you will use Group #1: 2 bolts Group #3: 1 bolt, 1 nut
Group #2: 2 nuts
Remember: When trying to balance the two sides of the scale you can only add groups 1 and 2 to the left pan, and you can only add group 3 to the right pan!
In the blanks below, enter how many of each group you used to get the balance to be even. Then record how many bolts, washers, and nuts in each pan. Make sure your teacher has checked your answers before moving on to the next situation.
Left Pan
# of Group 1 # of Group 2
# of Bolts # of Washers # of Nuts
# of Group 3
# of Bolts
Right Pan
# of Washers # of Nuts

Left Pan Right Pan
The groups you will use
Group 1: 2 bolts, 1 washer, 3 nuts
Group 2: 2 bolts
Group 3: 2 washers
Group 4: 2 nuts
Remember: When trying to balance the two sides of the scale you can only add group 1 to the left pan, and you can only add groups 2, 3, and 4 to the right pan!
Left Pan
# of Group 1
# of Bolts # of Washers # of Nuts
Right Pan
# of Group 2 # of Group 3 # of Group 4
# of Bolts # of Washers # of Nuts
Left Pan Right Pan
The groups you will use
Group 1: 1 bolt, 3 washers,
3 nuts
Group 2: 2 bolts 3 nuts
Group 3: 2 washers, 1 nut
Remember: When trying to balance the two sides of the scale you can only add group 1 to the left pan, and you can only add groups 2 and 3 to the right pan!
Left Pan
# of Group 1
# of Bolts # of Washers # of Nuts
Right Pan
# of Group 2 # of Group 3
# of Bolts # of Washers # of Nuts

Left Pan Right Pan
The groups you will use
Group 1: 1 bolt, 1 washer, 1 nut
Group 3: 1 bolt
Group 2: 1 bolt, 1 nut
Group 4: 1 bolt, 1 washer, 3 nuts
Remember: When trying to balance the two sides of the scale you can only add groups 1 and 2 to the left pan, and you can only add groups 3 and 4 to the right pan!
Left Pan
# of Group 1 # of Group 2
Right Pan
# of Group 3 # of Group 4
# of Bolts # of Washers # of Nuts # of Bolts # of Washers # of Nuts

Balancing with Bolts
Teacher Answer Key
Situation #1:
Left Pan
# of Group 1 # of Group 2
1 1
# of Bolts # of Washers # of Nuts
0 2 2
Situation #2:
Left Pan
# of Group 1
2
# of Bolts # of Washers # of Nuts
2 6 4
Situation #3:
Left Pan
# of Group 1
2
# of Bolts # of Washers # of Nuts
6 6 2
Situation #4:
Left Pan
# of Group 1 # of Group 2
1 2
# of Bolts # of Washers # of Nuts
3 1 3
# of Group 3
2
# of Bolts
2
Right Pan
# of Washers # of Nuts
0 2
Right Pan
# of Group 2 # of Group 3 # of Group 4
2
# of Bolts
4
1
# of Washers
2
3
# of Nuts
6
Right Pan
# of Group 2 # of Group 3
1
# of Bolts
2
3
# of Washers
6
# of Nuts
6
Right Pan
# of Group 3 # of Group 4
2
# of Bolts
3
1
# of Washers
1
# of Nuts
3