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Cells and Systems 6-8 / Week 06 / Nature Day
6/6
Week 06 · Systems Work Together

Nature Day

Nature Day: The talk test walk
// Lungs, heart and muscles share one job
⏱ about 20 min

Nature Day: The Talk Test Walk

Saturday, the whole family sets off on a walk, the Windowsill Log tucked under Raven's arm.

"Flat part first," Rocket says. "Everyone say a sentence." Everyone does, easily.

The path tilts uphill. "Now sing," Raven says. The song gets ragged and everyone laughs.

"What do you notice?" Raven asks. "The hill changed what our mouths could do."

Nova glides ahead to the top. "Your legs asked for more oxygen," she says. "Which two systems answered?"

"Lungs and heart," Rocket pants. At the top they sit, count breaths for a minute, and compare.

"Everyone went up," Raven says, writing. "Different numbers, same direction."

  1. The body is a system of interacting subsystems, each made of groups of cells.
  2. The lungs bring oxygen into the body and remove carbon dioxide. Gas exchange happens only in the alveoli.
  3. The circulatory system, vessels and a pump, carries oxygen to every tissue and brings carbon dioxide back.
  4. Muscle cells release energy from sugar using oxygen, so working muscles need more oxygen.
  5. Breaths and beats rise together after exercise, and a breathing center in the brain helps regulate it.
◇ FAMILY TALK TEST WALK
Walk together on flat ground for five minutes. Everyone says a full sentence out loud.
Walk a little faster, or up a gentle slope, for two minutes. Try to sing a line of a song.
Sit down together. Each person counts breaths for one minute. Compare: did everyone's number go up?
Talk it over: which system brought in the oxygen, and which one delivered it to your legs?
For a grown-up
Breath counts today are science readings only, like seedling heights. They are not a health check.
Keep the walk gentle and on familiar ground, with shoes on. Anyone who feels dizzy sits and drinks water.
Look at animals and plants from where you stand. Nothing is touched or picked.
The talk test and breathing facts come from the MedlinePlus medical encyclopedia and OpenStax biology texts, both free online.
Safety first
Walk only as fast and as far as everyone is used to. Stop and sit if anyone feels dizzy.
Never touch an insect, a nest or an unknown plant or berry along the way.
Wash your hands when you get home.
THINK IT THROUGH
  • Read the question.
  • Tap your answer.
On the hill, everyone could talk but not sing. What does the talk test call that level?
Everyone's breath count went up after the hill. Which system brought in more oxygen?
Which system delivered that oxygen to the leg muscles?
How many systems did the recap name as sharing the job of getting oxygen to working muscles? Type a number.
WHY THIS EXERCISECounting the systems is the first step in arguing that they interact.
Draw your family on the hill. Give each person a speech bubble showing how many breaths they counted.
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