When students learn new concepts, they should first tap into previous knowledge and then extend those ideas. A matching game that reinforces opposites will lay the foundation for moving on to positive and negative numbers. Pairs of opposite words, such as hot and cold, above and below, more than and less than and minus 12 and plus 12, are written on index cards. The cards are placed face down, and players take turns trying to turn over a match. When all cards have been picked up, the person with the most cards wins.
Everyday situations should be emphasized when teaching negative numbers. Write situations on index cards that depict positive and negative numbers. For example, a $9 debt, 10 feet below sea level, 8 feet above sea level, five floors below ground level, six seconds to blast off or two degrees above zero. Using chalk, draw a large number line from -10 to +10 on the sidewalk. The student chooses one of the cards and walks off the steps. He begins on zero and moves forward for positive numbers and backward for negative numbers. This works well with more than one child taking turns.
When students understand how numbers fall on a number line, they can begin to compare them. Two number lines are drawn on a white board, one vertical and one horizontal, just to emphasize that a number line can go in either direction. Remind students that a negative number has a minus sign in front, and a positive number can have a plus sign or no sign at all. Write two numbers on the white board, such as -9 and -3, leaving room between them for a comparing sign: greater than >, less than < or equals =. The child chooses the correct sign and uses the number line as a visual aid when explaining his choice: -9 < -3.
Students can relate to warm and cold temperatures. They can look up the coldest and hottest spots in the country on any given day. Discuss temperatures and then write numbers on index cards that represent temperatures above and below zero. Two or more children can play a game with the cards. Players split the cards evenly and stack them face down. They turn over their top cards, and whoever has the warmest temperature picks up the cards. The winner is the person who picks up the most cards.
Once a child understands the concept of negative numbers, she’s ready to make more meaningful connections. Give her a number such as -8, and she can come up with a phrase to match it: “Sam didn’t have any money, so he borrowed $8 from his friend for the movie.” Next, move to two numbers, such as -5 and 10: “The football team moved ahead 10 yards, but were pushed back 5 yards for a penalty.”