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Balancing Equations with Note Cards Mark as Favorite (104 Favorites)

ACTIVITY in Balancing Equations, Conservation of Mass. Last updated January 29, 2024.


In this activity, students will balance equations and get immediate feedback on whether they are accurate or not while trying to solve a challenge. This activity works best as a review activity after balancing and the law of conservation of matter has been taught.

Grade Level

High and Middle School

NGSS Alignment

This activity will help prepare your students to meet the performance expectations in the following standards:

  • HS-PS1-7: Use mathematical representation to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.
  • Scientific and Engineering Practices:
    • Using Mathematics and Computational Thinking


By the end of this activity, students should be able to

  • Balance equations.
  • Apply the law of conservation of matter.
  • Distinguish between reactants and products.
  • Differentiate between coefficients and subscripts in chemical formulas.

Chemistry Topics

This activity supports students’ understanding of

  • Chemical Reactions
  • Balancing equations
  • Law of conservation of matter


Teacher Preparation: 10 minutes

Lesson: 30 minutes


  • Balancing Equations Activity Worksheet
  • 22 Note Cards/Index Cards
  • Create 1 Set of Balancing Equations Note Cards (for entire class)


  • No specific safety precautions need to be observed for this activity.

Teacher Notes

  • In this activity, students will be given a worksheet containing various chemical equations to balance. These reactions vary in difficulty.
  • Students will balance the equations and then walk to a table containing pre-made note cards. Each note card contains the correct coefficient values for an equation on the worksheet. The coefficients are listed in the same order as the blank spaces on the worksheet.
  • For each equation students will find the note card that matches the coefficients that they used and flip it over to determine the letter to the mystery quote that it represents. Students might balance the equation incorrectly but still find a note card that matches their coefficients.
  • The students will use their mystery quote to determine if their balancing is accurate. If students are creating words that logically fit together then they are on the right track, if they are not creating words or if the words do not make sense in their sentence this gives them immediate feedback that they are doing something incorrectly and need to retry or ask the teacher for help. Once students have correctly balanced all equations, they will have found all the letters to correctly solve the mystery quote.
  • This activity works best if students work independently or in pairs. If students work in pairs they should alternate between writing and looking up cards. If this isn’t stated, the stronger student will do all the work while the other just watches.
  • The teacher should monitor students and make sure they are not cheating. Sometimes students will just grab note cards looking for a specific letter that they know they need. I have a one card rule, meaning students are only allowed to turn over one card per trip to the front table.
  • Teacher should be ready to answer questions and help find solutions to where students are making mistakes. This activity will help encourage students to ask questions when they are stuck because they won’t be able to determine the answers if they keep making the same mistakes.
  • Students may work on the questions in any order that they choose. For my weaker students, I recommend them choosing problems that are solutions to a small word in the challenge phrase so they know immediately if they are making mistakes.
  • The majority of students will complete this activity within 30 minutes.If you have a lower level class or group of students who are struggling with this skill you may want them to complete the balancing outside of class and check the note cards first thing the next class periods.
  • An Answer Key is provided for teacher reference.
  • You can use the values and letters in the table below to create your note card set. Pictures are provided as an example.
  • Alternately, you can print out the downloadable cards provided to use with students. Print double-sided, flip on short side. I suggest printing on cardstock if possible. Check to make sure coefficients and letters are properly aligned, and paper handling may vary in different printers.
Front Back
4, 1, 3, 2 E
2, 3, 2 I
1, 2, 1 E
2, 1, 1, 2 A
2, 1, 2 R
1, 2, 1, 2 I
2, 2, 3 A
3, 2, 2, 3 O
2, 3, 1, 6 S
4, 5, 2 T
2, 13, 8, 10 F
1, 1, 3 L
2, 1, 1 F
4, 1, 2 B
4, 3, 4, 3 A
3, 1, 3, 1 E
1, 12, 10, 4 N
1, 3, 2, 3 T
3, 2, 1, 3 A
4, 3, 1, 12 C
1, 6, 2, 6 L
4, 5, 4, 6 M

For the Student



The law of conservation of matter states that matter cannot be created or destroyed.Therefore during any chemical change, elements cannot be added or lost; they are only rearranged to form new substances. In order for this to work, coefficients must be added in front of chemical formulas to balance reactions so that the same number of atoms are found on both sides of the chemical reaction for each element. You will be using this concept today to balance a series of equations to determine a mystery quote.

Pre-lab Questions

  1. Determine the number of atoms of each element in the following chemical formulas:

Number of H:
Number of C:
Number of O:

b.3 H2O
Number of H:
Number of O:

Number of Ca:
Number of N:
Number of O:


Balance the provided equations to solve the challenge phrase.


  1. All note cards are placed on the front desk in the lab. Please do not remove these cards from the table.
  2. Balance the chemical equations provided independently or with a partner. These can be completed in any order.
  3. After balancing an equation find the note card with the same sequence of coefficients on it that you used to balance the equation.
  4. Flip the note card and record the corresponding letter. Next, place the letter in the space provided in the mystery quote. Letters should spell words and complete a phrase if they are all accurate.
  5. If you cannot find your notecard or if you are not forming words, look back at your answers and try to determine your mistake. If you are struggling with determining your mistakes, please ask the teacher for help.


Mystery Letter

Chemical Equations


____ C + ____O2 + ____H2 →____C2H2OH


____Fe + ____Cl2 →____FeCl3


____C + ____ S → ____CS2


____NaOH + ____CaBr2→ ____Ca(OH)2 + ____ NaBr


____SO2 + ____O2 → ____SO3


____CH4 + ____ O2 → ____CO2 + ____ H2O


____NaN3 → ____Na + ____N2


____Mg + ____AlCl3 → ____Al + ____MgCl2


____Al(NO3)3 + ____H2SO4 → ____Al2(SO4)3 + ____HNO3


____V + ____O2 → ____V2O5


____C4H10 + ____O2 → ____CO2 + ____H2O


____Al2(CO3)3 → ____Al2O3 + ____CO2


____HI → ____H2 + ____I2


____FeO + ____O2 → ____Fe2O3


____Fe + ____Sn(NO3)4 → ____Fe(NO3)3 + ____Sn


____Li + ____AuCl3 → ____LiCl + ____Au


____C10H8 + ____O2 → ____CO2 + ____H2O


____C2H6O + ____O2 → ____CO2 + ____H2O


____Zn + ____H3PO4 → ____Zn3(PO4)2 + _____H2


____(NH4)3PO4 + _____Pb(NO3)4 → ____Pb3(PO4)4 + ____NH4NO3


____B2Br6 + _____HNO3 → ____B(NO3)3 + ____HBr


____NH3 + ____O2 → ____NO + ____H2O

Mystery Quote
























In one to two sentences, explain how the law of conservation of matter applies to balancing chemical equations.