Plus or Minus

Plus or Minus – Teacher Information

Grade Level:    2nd and 3rd grade

Materials Needed:

• 1 deck of cards per 2-4 person group
• Copy of Student Worksheet for each student

Learning Goals:

• Solidify understanding of addition and subtraction of small numbers (10 or less)
• Introduction to addition and subtraction of more than two numbers
• Development of problem solving skills and math based strategies

NCTM Standards that are addressed:

• count with understanding and recognize "how many" in sets of objects;

• use multiple models to develop initial understandings of place value and the base-ten number system

• develop understanding of the relative position and magnitude of whole numbers and of ordinal and cardinal numbers and their connections

• develop a sense of whole numbers and represent and use them in flexible ways, including relating, composing, and decomposing numbers;

Plus or Minus – Instructions

Description: Plus or Minus is a card game similar to the well known games “Crazy Eights” and “Uno”.  The rules have been modified so that players can work on their addition and subtraction skills.

Goal: the goal of the game is to get rid of all of the cards in your hand.  If at any point a player has no cards left the game is over and they win.  Also, if the draw pile is empty the game ends and the player with the fewest cards in hand wins.

Setup: REMOVE ALL FACE CARDS FROM THE GAME, THEY ARE NOT USED (jacks, queens, and kings). Each player is dealt eight cards. The remaining cards are placed in a pile between the players, this is the draw pile.  Finally the top two cards from the draw pile are turned over and placed in the two discard piles next to the draw pile. (shown below)

On your turn: Starting with the player left of the dealer each player takes turns playing one card.  If you do not have an available play (see “what you can play” below) on your turn you must draw a card.  At this point you can play your new card if it is an acceptable play. If you still do not have a play, pass to the next player. *IMPORTANT* If all players in the game have taken an unsuccessful turn at the same combination of two cards then flip the next two cards in the draw pile and place them on top of the discard piles.

What you can play: This is where your addition and subtraction skills will help you play.  You may only play a number that is the SUM or DIFFERENCE of the two face-up cards on the discard piles For example: The face up cards are a 4 and a 6 so I can play either a 2 or a 10.  A few stipulations are listed below for clarification:

• Aces = 1
• Any sum greater than 10 should have 10 subtracted from it. (Example: 5 plus 7 = 12 but subtract 10 to get 2 as an available play)
• If on the original flip two of the same number are flipped (Example: two 5’s) then put them back and flip again.
• The suit of the cards played DOES NOT MATTER

Variation: (FOR AN ADDED CHALLENGE)  Instead of using the previous two cards in the discard line, try using the previous three cards added and subtracted in any way to get the possible plays.

Plus or Minus – Student Worksheet

Section A: Complete before playing

• Do the addition and subtraction problems listed below.
• IF ANY SUM IS LARGER THAN 10 subtract 10 from it and put the new answer in the middle column labeled “Minus 10”

• Now try to solve these combined addition and subtraction problems
• When you can do the bottom half of this worksheet correctly try moving on to the variation game listed at the end of the instruction sheet.

A)   2+4-1=                                        B)   4+5-3=                            C)   3+1+6=

D)   7-2-3=                                         E)   2+7-4=                             F)   8-5-1=

G)   2+9-4=                                        H)   4+1-3=                            I)   7-2+4=
Section B: Complete after playing

• Questions for students

1. Did anyone in your game get rid of all of their cards? If not how many cards did the winning player have left at the end?

1. Did players tend to count out loud the possible plays?  Were players helping other players by stating possible plays (especially in the variation game listed at the bottom of the directions?)

1. Did anyone in your group discover any strategies to winning? How might your strategy be different if you are playing with two people compared to a larger group?

1. Can your group think of any additional rules that might make the game more interesting or add more skill to winning?

This lessons is written by students at Massachusetts Institute of Technology (M.I.T.), as part of their coursework for 11.124, Introduction to Teaching and Learning Science and Math.