This game focuses on estimating the total cost of multiple whole-dollar items.

• Concept Focus: Estimating the total sum of whole-dollar amounts.

• Materials Needed:

  1. "Items for Sale" posters or cards: Display 5–8 items with whole-dollar prices (e.g., Toy Car: $12, Book: $8, T-Shirt: $19, Soccer Ball: $25). Keep the prices relatively low so the totals are manageable.

  2. Large whiteboard/chalkboard to record bids and totals.

  3. Dry-erase markers for teams.

• How to Play (Whole Class or Teams):

  1. Form Groups: Divide the class into 4–5 teams (or play as one whole class, simply shouting out answers).

  2. The Shopping List: The teacher names two or three items to "buy" together (e.g., "We're buying the Toy Car and the T-Shirt!").

  3. The Bid (Estimate): Each team quickly estimates the total cost by rounding the whole dollar amounts (e.g., $12→$10, $19→$20. Estimate: $10+$20=$30). They write this estimate on their whiteboard. This is their "bid."

  4. The Auction: Teams show their bids. The teacher asks the group with the best estimation strategy to explain their rounding.

  5. The Total: The teacher or a student calculates the actual total cost ($12+$19=$31).

  6. Scoring: Points are awarded for the closest estimate and for correctly calculating the actual total. The team with the most points wins the auction.

  7. Extension: Introduce a "budget" (e.g., $50). After estimating the cost of the items, teams must quickly estimate if they are under or over budget.

This highly interactive game focuses on calculating change using the inverse/counting-up strategy.

Concept Focus: Calculating change using whole-dollar amounts and the count-up method (an inverse operation strategy).

Materials Needed:

• 1. Large flashcards with a single, whole-dollar Item Price (e.g., $18).

  2. A set of $5, $10, and $20 New Zealand dollar note replicas (large visuals for the class).

  3. Whiteboard to track the "running total."

• How to Play (Whole Class Relay):

  1. Set the Price: The teacher shows a flashcard (e.g., Item Price is $18).

  2. Payment: The teacher announces the amount paid (e.g., "The customer paid with a $50 note!").

  3. The Chain: The class works together, with students taking turns to "give change" by counting up to the amount paid.

     • Student 1 (The Buyer): Starts at the price ($18).

     • Student 2 (The Cashier): Says, "$18. Plus $2 makes $20." (Holds up a $2 coin visual). Change given so far: $2.

     • Student 3: Says, "$20. Plus $30 makes $50." (Holds up a $20 and a $10 note visual). Change given so far: $2+$30=$32.

     • Student 4 (The Checker): States the final change: $32.

  4. Inverse Check: The teacher or student checks the calculation using the inverse operation: Price + Change = Amount Paid ($18+$32=$50).

  5. Scoring: If the class successfully completes the chain and the inverse check is correct, they earn a point. If they get stuck, reset with a new price.

  6. Tip: Encourage the use of mental jumps to the nearest whole $10 or $100 to reinforce quick change calculation.