Incredible Equations – Math Calendar Activity

Exploring Addition & Subtraction With Manipulatives

Lesson 366 • By Amy (Expanded Version)
Grade Level: Kindergarten

Learning Objectives

Students will:

  • Build, model, and explain addition and subtraction equations.
  • Use concrete objects (candy, cereal, bingo chips) to show number combinations.
  • Practice decomposing a number into two parts.
  • Write or verbalize equations using proper math language.
  • Recognize that the day’s date can be represented using many different number stories.

Materials

  • Large index cards
  • Bingo chips OR small food items (marshmallows, Cheerios, M&Ms, etc.)
  • Laminator or page protectors
  • Markers
  • Whiteboard or chart labeled “Incredible Equations!”
  • Optional: dry erase markers, math journals

Preparation

1. Create Reusable Equation Cards

On each large index card:

  • Draw a box → then a plus sign → then another box → then an equals sign.
  • On the back, draw the same setup but with a minus sign instead of a plus sign.

Example (front):
[ □ ] + [ □ ] =

Example (back):
[ □ ] – [ □ ] =

Laminate cards OR place them in page protectors.

2. Gather Manipulatives

Prepare a small cup or baggie of:

  • M&Ms
  • Marshmallows
  • Cereal
  • Bingo chips
    (You can rotate items to keep interest high!)

Activity Procedure (Whole Group or Small Groups)

1. Start With the Calendar

Use the day of the month as the target number.
Example: Today is the 9th → target number is 9.

Write the number big and bold at the top of the board and circle it:

9

2. Give Each Student Their Equation Card + 9 Items

Say:

“Your job is to separate these into two groups and make an addition equation that equals 9.”

3. Students Build Their Equations

Children physically divide their items:

  • Some go in the first box
  • The rest go in the second box

4. Students Verbalize Their Math Sentence

Prompt:

  • “Tell me your equation.”
  • “How many in the first box?”
  • “How many in the second box?”
  • “How many altogether?”

Example:

“I have 5 in the first box and 4 in the second box.
Five plus four equals nine.”

5. Record on the “Incredible Equations” Board

Write student equations under today’s number:

  • 5 + 4 = 9
  • 2 + 7 = 9
  • 6 + 3 = 9
  • 1 + 8 = 9

Celebrate how many ways students represent the same total.

6. Extension: Subtraction Side

Flip the card to the subtraction version.

Students begin with 9 items in the first box, remove some to the second box, and verbalize:

“9 – 3 = 6”

These can also be added to the board.

Math Vocabulary to Introduce

  • Equation
  • Plus
  • Minus
  • Equals
  • Altogether
  • Take away
  • Number story
  • Parts and whole

Encourage complete sentences like:

“The parts are 5 and 4. The whole is 9.”

Differentiation

For Students Who Need Support

  • Give fewer items (e.g., use the number 5).
  • Use color-coded manipulatives.
  • Pair students for peer modeling.

For Students Ready for Challenge

  • Let them record several equations in a math journal.
  • Have them try three-part equations (e.g., 2 + 3 + 4 = 9).
  • Let them flip between addition & subtraction and write both for the same total.

✨ Optional Extensions

1. Daily Equation Book

Create a class booklet:

  • One page per day
  • Students contribute their best addition or subtraction equation
  • By the end of the month you have a whole class math book!

2. Story Problems

Students make up a simple math story:

“I had 9 marshmallows. I ate 2. How many left?”

3. Center Activity

Place equation cards + manipulatives at a math center for independent exploration.

4. Equation Rainbow

Use crayons to color each part a different color.

Assessment 

Ensure each child can:

  • Separate a number into two groups
  • Build an equation using objects
  • Name the equation aloud
  • Understand “part + part = whole”
  • Use manipulatives correctly

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