Expansion of chest with each breath in Respiration In Organisms – Class 7 Science Experiment
Chapter Name: Respiration In Organisms
Activity Name: Expansion of chest with each breath in Respiration In Organisms
Activity Description:

In this activity, you will measure the expansion of a person’s chest during breathing. By wrapping a measuring tape or twine around their chest and observing the changes in width while they breathe in and out deeply, you will explore how the chest expands and contracts during inspiration and expiration.
Required Items:
- Measuring tape or twine
Step by Step Procedure:
- Ask one of your friends to participate in the experiment.
- Take the measuring tape or twine and wrap it around your friend’s chest at the level of the diaphragm. Ensure that it’s not too tight but snug enough to get accurate measurements.
- Note down the initial width of the chest.
Experiment Observations:
- Observe the changes in the width of their chest as they breathe in and out.
- Record the measurements when the chest is at its widest (during inhalation) and narrowest (during exhalation).
Precautions:
- Ensure that the measuring tape or twine is not too tight, as it may restrict breathing or cause discomfort to your friend.
- Make sure your friend is breathing naturally and not trying to force their breath during the experiment.
Lesson Learnt from Experiment:
This experiment helps to understand the process of respiration, where the chest expands during inhalation and contracts during exhalation. When we breathe in, the diaphragm contracts, and the intercostal muscles expand the chest cavity, causing it to widen. Conversely, during exhalation, the diaphragm relaxes, and the intercostal muscles contract, reducing the chest cavity’s width.