Math in Our World: The Shrink-O-Matic
Cameron just invented The Shrink-O-Matic. It shrinks objects for 1 hour! You look through it like a camera, press one of the red fraction buttons, then press the X button to multiply, and —BOOM! — whatever you had it aimed at shrinks!
The fraction you push determines the new size of the object.
Cameron said, “If you aimed the Shrink-O-Matic at a 12-foot tall ladder and pushed the ⅓ button, it would shrink to ⅓ of its original size. Because ⅓ of 12 is 4, you’d now have a 4-foot tall ladder.”
He is excited to try out his new invention, and he started a list of things he might shrink.
| Object | Approximate Original Size |
|---|---|
| Swingset | 10 feet tall |
| Fire truck | 35 feet long |
| Apple tree | 30 feet tall |
| Skyscraper | 300 feet tall |
| His house | 24 feet tall |
| Airplane | 180 feet long |
- Use pictures, models, or numbers to show what is happening.
- What do you notice? What do you wonder?
- What mathematical questions can you ask about this situation? Answer all the questions you can!
- You can shrink an object to ½ of its original size by dividing by 2. How can this information help you figure out the size of an object shrunk to ⅓, ¼, or ⅕, of its size?
- How does knowing ⅓ of the size help you figure out ⅔ of the size?
- Show your work to someone else, and explain your thinking. Did they understand?
- Ask if they have any other questions you can answer!
If you shrink your whole family to ⅕ their original sizes, how big will each of you be? Sketch your mini-family and cut out the sketches. What sorts of adventures would you have?
Google doc for printing and copying
Activity for the Seesaw platform
Sample problems and solutions