Math Arguments
Problems, Questions, and Puzzles to spark discussion and argument in the maths classroom.
Fahrenheit to Celsius
We all know the conversion from °C to °F: multiply by 9/5 (or 1.8, if you can't handle those evil fractions) and then add 32. The conversion from °F to °C is the opposite process: subtract 32 and then multiply by 5/9 (or 0.555555555).
That's cumbersome for mental math. Here's a shortcut: subtract 30 and divide by 2 OR multiply by 2 and add 30.
Thoughts?
- How good is that shortcut?
- Are there temperatures that it's okay for?
- Are there other temperatures that the shortcut is too far off?
- Is this just another stupid shortcut? Should we NixTheTricks?
What other mathematical aspects of this caught your attention? What do you wonder about the situation?
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Source:
T.R.Milne
More Information:
Noticing and wondering is a tool to help students:
- Understand the story, the quantities, and the relationships in the problem.
- Understand what the problem is asking and what the answer will look like. Have some ideas to begin to solve the problem.
More Here at NCTM
Noticing and wondering is a tool to help students:
- Understand the story, the quantities, and the relationships in the problem.
- Understand what the problem is asking and what the answer will look like. Have some ideas to begin to solve the problem.
More Here at NCTM
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