Home›Lesson Plans›Science›Chemistry · Grade 10

Balancing Equations: Conserving Every Atom

Students learn to balance chemical equations — adjusting coefficients so every atom is accounted for on both sides — putting the law of conservation of mass into practice, one reaction at a time.

Grade 10Reactions55 minutes1 class period5E ModelExplicit teaching4 StandardsCommon Core
Start the Lesson
Assign or share this lesson

Copy link works with Canvas, Schoology, Moodle and any other LMS — paste it in as a resource or assignment.

Lesson at a Glance

Everything you need before the bell rings

Learning Objectives

Students will be able to…

  • ✓Explain conservation of mass in equations.
  • ✓Count atoms on each side.
  • ✓Use coefficients to balance.
  • ✓Balance simple equations.
Essential Question

In a chemical reaction, atoms are never created or destroyed — only rearranged. So how do we write equations that honor this rule exactly?

0
Lesson Phases
0
Vocabulary Terms
0
Standards Aligned
0
Interactive Task
Balance It · Interactive

Balance the Equation

Project each item and have students choose the correctly balanced equation. The tool shows the atom count on each side.

⚖️ Which equation is correctly balanced?Try it
Choose the balanced equation and explain why.
The Lesson · 5E Model

55 minutes, five moves

Tap any phase to open the teacher moves and student actions.

1

Engage — Atoms In = Atoms Out

5 min

If atoms can’t vanish, what must be true of every equation?

👩‍🏫 Teacher Moves

  • State conservation of mass.
  • Ask what it means for equations.
  • Set the goal: balancing.

🎒 Student Actions

  • Recall conservation.
  • Apply it.
  • Predict the rule.
2

Explore — Balance Together

12 min

Students investigate.

👩‍🏫 Teacher Moves

  • Send students to Balance the Equation.
  • Count atoms on each side.
  • Choose the balanced one.

🎒 Student Actions

  • Count atoms.
  • Compare sides.
  • Choose balanced.
3

Explain — Coefficients

13 min

Teacher explains.

👩‍🏫 Teacher Moves

  • Count each atom type.
  • Add coefficients (not subscripts).
  • Recount to confirm balance.

🎒 Student Actions

  • Count atoms.
  • Add coefficients.
  • Confirm balance.
4

Elaborate — Elaborate — Balance More

12 min

Apply.

👩‍🏫 Teacher Moves

  • Balance new equations.
  • Check with an atom tally.
  • Explain each choice.

🎒 Student Actions

  • Balance them.
  • Tally atoms.
  • Explain choices.
5

Evaluate — Evaluate — Exit Ticket

5 min

Three quick checks.

👩‍🏫 Teacher Moves

  • Hand out the exit ticket.
  • Look for atom counting.
  • Collect as formative data.

🎒 Student Actions

  • Balance one.
  • Count atoms.
  • Explain conservation.
Standards Alignment

Built to the standards you report on

Aligned to the Next Generation Science Standards (High School Chemistry) and Common Core literacy in science.

NGSS
HS-PS1-7

Use mathematical representations to support the claim that atoms are conserved in a reaction.

NGSS
HS-PS1-2

Construct an explanation for reaction outcomes based on patterns.

NGSS
HS-PS1-4

Develop a model to illustrate energy change in a reaction.

CCSS
RST.9-10.3

Follow precisely a complex multistep procedure.

Differentiation

One lesson, every learner

Multilingual Learners

ELL / EMERGING READERS
  • Atom-counting chart.
  • Sentence frame: “___ atoms on each side.”
  • Use atom models.

Support & Access

IEP / 504
  • Start with a pre-counted equation.
  • Only change coefficients.
  • Count with a chart.

Stretch & Extend

GIFTED / EARLY FINISHERS
  • Balance harder equations.
  • Balance combustion reactions.
  • Introduce mole ratios.
Materials

What to gather

  • 📽️Projector / board
  • 📓Science notebooks
  • 💻Balance the Equation
  • 🧱Atom models
  • ✏️Pencils
  • 🎫Exit-ticket slips
Vocabulary

Key terms — hover for a quick definition

chemical equationa symbolic representation of a reactionreactanta starting substance (left of the arrow)producta substance formed (right of the arrow)coefficienta number in front of a formulasubscripta small number within a formulaconservation of massmatter is neither created nor destroyedbalanced equationequal atoms of each element on both sidesformulasymbols showing a compound’s atoms
Evaluate

Exit Ticket

Preview the three formative checks. Tap “Sample answer” to see what mastery looks like — hide them before you print for students.

QUESTION 1
In the equation 2H₂ + O₂ → 2H₂O, how many oxygen atoms are on each side?
Two on each side (balanced).
QUESTION 2
When balancing, do you change coefficients or subscripts?
Coefficients (the big numbers in front) — changing subscripts would change the substance itself.
QUESTION 3
What law requires equations to be balanced?
The law of conservation of mass.

Going deeper? Mole ratios.

Have students use the coefficients of a balanced equation as mole ratios to predict how much product forms. A printable balancing sheet is in the Science library.

Study · Flashcards

Study the key terms

Tap a card to flip it, then rate whether you knew it. Built from this lesson’s vocabulary.

🃏 Balancing Chemical EquationsFlip
Card 1
Term
Tap to flip →
Meaning
0

Nice work!

Practice · Quiz

Check your understanding

A quick self-check with instant feedback, drawn from this lesson’s key terms.

📝 Balancing Chemical EquationsQuiz
Score: 0
1 / 6
Question 1
0%

Nice work!

Practice · Worksheet

Printable worksheet

A print-and-go review sheet with a built-in answer key. Tap “Show answer key” to reveal answers, or print the clean version for students.

🖨️ Balancing Chemical EquationsPrint
Name: ________________________
Date: ____________

Part A · Write the word that matches each meaning

Word bank: balanced equation, chemical equation, coefficient, conservation of mass, formula, product, reactant, subscript
  1. a symbolic representation of a reaction
  2. symbols showing a compound’s atoms
  3. a small number within a formula
  4. equal atoms of each element on both sides
  5. matter is neither created nor destroyed
  6. a number in front of a formula
  7. a substance formed (right of the arrow)
  8. a starting substance (left of the arrow)

Part B · Show what you learned

  1. In the equation 2H₂ + O₂ → 2H₂O, how many oxygen atoms are on each side?
  2. When balancing, do you change coefficients or subscripts?
  3. What law requires equations to be balanced?
Answer key — Part A: 1) chemical equation · 2) formula · 3) subscript · 4) balanced equation · 5) conservation of mass · 6) coefficient · 7) product · 8) reactant
Part B: 1) Two on each side (balanced). 2) Coefficients (the big numbers in front) — changing subscripts would change the substance itself. 3) The law of conservation of mass.