TITLE: Weighing Inequalities

SUBJECT: Pre-Algebra, 7th grade

TOPIC: Formulating Inequalities

INTERACTIVITY: The directions involve hanging each of 3 animals from each of 4 balloons (one at a time). The animals each have a small plastic hook on their head, which will hook onto a small black ring under the balloons. Based on whether the balloon and the animal fall “to the ground” or hang in the air, the student decides how heavy the animal is. By filling in the worksheet, they are guided to make conclusions about which animal is heaviest (and lightest, etc.). See the directions for details.

DIRECTIONS:

- Hang the turtle from the orange balloon.
- Does he fall to the ground? ________
- Since the orange balloon holds up 5 lbs, we know that the turtle weighs _______ 5 lbs. (more than or less than)
- Written as an inequality, the turtle _______ 5lbs. ( < or > )

- Now hang the turtle from the yellow balloon.
- Does he fall to the ground? ________
- Since the yellow balloon holds up 20 lbs, we know that the turtle weighs ______ 20 lbs. (more than or less than)
- Written as an inequality, the turtle _______ 20 lbs. ( < or > )

- Now hang the turtle from the green balloon.
- Does he fall to the ground? ________
- Since the green balloon holds up 50 lbs, we know that the turtle weighs _______ 50 lbs. (more than or less than)
- Written as an inequality, the turtle _______ 50 lbs. ( < or > )

- Finally, hang the turtle from the blue balloon.
- Does he fall to the ground? ________
- Since the blue balloon holds up 100 lbs, we know that the turtle weighs ______ 100 lbs. (more than or less than)
- Written as an inequality, the turtle _______ 100 lbs. ( < or > )

- Now what can we say about the turtle's weight?
- Using your inequalities above, fill in the following blanks with the number of pounds: ________lbs. < turtle < ________lbs. (Hint: first blank: Which balloon still let the turtle fall? Second blank: Which balloon held up the turtle?)
- *Try to use the smallest range possible.

- Complete the same steps using the lion and the pig. At the end, put the animals in order from lightest to heaviest, based on the inequalities that you found.

TIME: This activity will probably take a student about 15 minutes to complete.

SPECIAL CONSTRUCTION: I used retractable keychain pulls for the middle two balloons. They have slightly different tensions, so they hold different weights. The smallest balloon is simply a stretchy jewelry string that will stretch out no matter what weight is on it. The biggest balloon is on a string that does not stretch at all. Each balloon has a short string hanging off the bottom, ending in a small rubber “o” ring. The stuffed animals were made heavier by sewing rocks inside of them. The turtle does not have rocks in it, the pig has a few, and the lion is rather heavy.

CREDIT: The students can receive up to 10 points of extra credit by completing the worksheet.

OTHER COMMENTS: This bulletin board depends heavily on the correct materials. Without the right keychain pulls, the results would be inaccurate.