This is a manipulative that also can be used as a game or math center activity to practice adding and subtracting positive and negative numbers.
There are many ways to teach adding positive and negative numbers, but the method I found that worked best for my middle school students was using a hot air balloon analogy. Hot air represents positive numbers and sandbags represent negative numbers. Adding hot air will cause the balloon to rise, while adding sandbags causes the balloon to go down. Furthermore, if hot air is removed (subtracted) from the balloon, the balloon goes down, and if sandbags are removed (subtracted) the balloon rises.
This manipulative/game contains a sheet of hot air balloons and a cliff with a vertical number line that can be printed out for each student. Students can place their hot air balloon on the first number in their addition or subtraction problem and then move it up when adding hot air (or a positive number) or move it down when adding sandbags (or a negative number). Where they land is the answer to the addition problem. As an example, for the problem 2 + -5, students would place their balloon on the 2. Since they are adding sandbags, they move their balloon down 5 units, which lands them on the answer, -3. For subtraction, the students will again place their balloon on the first number in the problem and then move it up if they remove sandbags (or subtract a negative number) or down if they remove hot air (or subtract a positive number). For the problem -4 - 3, the students would place their balloon on the -4 and since they are removing hot air, their balloon moves down 3 units and lands on -7, the answer.
Additional instructions and cards are included to turn this manipulative into a fun game perfect for a math center or for small groups of students to play to practice adding and subtracting integers.
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