Order-of-Magnitude Estimation
How many breaths do you take in a lifetime?
Cheryl Anderson
As an introduction to the respiratory system and “hook” for students, I will have them determine the number of breaths they take in a lifetime.
Pre-test:
In order to assess students’ current knowledge of the respiratory system, I will have them complete a quick write on sticky notes. They will be timed for 1 minute and given the prompt, “Write everything you know or have heard about the respiratory system”. At the end of the minute, I will have the kids post their notes on the board. Before going over them, I will ask them “How many breaths do you think you take in a day? In a lifetime? Have them write a knowledgeable guess after collaborating in groups of 3-4 students.
Objectives:
- What is the primary function of the respiratory system?
- List the features of alveoli that adapt them to gas exchange.
- State the difference between ventilation, gas exchange and cell respiration.
- Explain the mechanism of ventilation in human lungs including the action of the internal and external intercostal muscles, the diaphragm and the abdominal muscles.
Hook (catch):
In student groups, as above, students will collaborate to solve the problem of how many breaths they take in a day.
Activity: Expand the question to how many breaths in a lifetime. (They would have to know the average lifespan of a person, how many breaths in a minute and then calculate how many per hour, etc. or something similar.)
Review: After discussion and ideas for solutions, students will begin learning the objectives of the respiratory system. We will then address the sticky notes and classify them (through discussion) as true, not true or unsure. These will be saved as we move through the unit on the respiratory system. We will refer to them as part of our closing each day and move them or eliminate them accordingly.
Assessment: How many breaths does the average human take in a lifetime? Explain how you arrived at your answer.
Post Test: As part of the post test for the respiratory system unit, students will be asked how many breaths in a lifetime and how they thought about the problem. This assessment will include questions and identification of respiratory organs.
Solution: On average, a person at rest takes about 16 breaths per minute. This means we breathe about 960 breaths an hour, 23,040 breaths a day, 8,409,600 a year. Unless we get a lot of exercise. The person who lives to 80 will take about 672,768,000 breaths in a lifetime.
Standards Addressed:
P- Pre-test
O – Objectives
C – Catch (hook) cannot be a question (like the jar of candy sitting in the middle of the table to pique interest)
A – activity (Resources template from OoM website)
R – Review
A –assessment
P – Post Assessment
S - Standards