Building a model of the respiratory system asks your student to construct a working lung model from a clear plastic bottle, a Y-shaped straw connector, two small balloons representing the lungs, and a large balloon stretched across the cut bottom to stand in for the diaphragm. The sheet walks through a seven-step procedure, a hypothesis section, and two specific observation prompts: what happens to the lung balloons when the diaphragm balloon is pulled down, and what happens when it is pushed up. This lab is well-suited for grades 4 to 6 and targets the core question of how diaphragm movement drives inhalation and exhalation.

The recording sheet fits cleanly into a human body unit study, pairing naturally with lessons on the circulatory system or gas exchange. A student who completes the observations and conclusion can articulate the mechanical relationship between the diaphragm and lung volume, which is a measurable outcome for any life science scope and sequence. The Think Further prompt, asking how exercise affects breathing rate, gives your homeschooler an easy bridge into a follow-up investigation.