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Cells and Systems 6-8 / Week 05 / Nature Day
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Week 05 · Cells to Tissues to Organs

Nature Day

Nature Day: Organisms on a walk
// Levels of organization in a living body
⏱ about 20 min

Nature Day: Organisms on a Walk

Saturday morning, the crew heads out the back door with the Windowsill Log under Raven's arm.

"Every tree is an organism," Rocket announces, pointing. "That one. That one. That bird!"

Raven stops at a flower bed. "What do you notice? Each plant here is one organism, but a bee is one too."

Nova hovers above the path. "Organisms come in every size," she says. "Count how many kinds you can spot in two minutes."

They count seven. Then they walk briskly to the end of the street and back.

Rocket sits on the step and presses two fingers to his wrist. "Walking pulse," he says. "Science reading number four."

  1. Living things are organized on a ladder: cell, tissue, organ, organ system, organism.
  2. A tissue is a group of similar cells with one function. An organ is tissues grouped for a common function.
  3. The heart is an organ about the size of a fist, built of cardiac muscle tissue, with four chambers.
  4. The pulse is the number of heartbeats per minute, counted with two fingers on the wrist after ten minutes of rest.
  5. A table from the National Library of Medicine gives resting ranges by age, and a range is a stretch of usual numbers.
◇ FAMILY ORGANISM COUNT
Walk together for ten minutes. Everyone points out organisms: trees, plants, birds, insects, pets.
Keep a tally. Which kind of organism did you see most? Which was the biggest and which the smallest?
Back home, everyone sits for ten minutes, then counts a resting pulse for 30 seconds and doubles it.
Talk it over: every organism you saw is made of cells. Where is the ladder in a bird?
For a grown-up
Pulse counts today are science readings only, like the seedling heights in the Log. They are not a health check.
Please keep the walk gentle, on flat ground, with shoes on. Anyone who feels dizzy sits down and drinks water.
Look at insects, nests and unknown plants from where you stand. Nothing is touched or picked.
The levels of organization come from OpenStax Concepts of Biology, and the pulse method from the MedlinePlus medical encyclopedia.
Safety first
Look at animals, insects and nests from where you stand. Never touch an insect, a nest or an unknown plant or berry.
Count a pulse with two fingers on the wrist, never on the neck.
Wash your hands when you come back inside.
THINK IT THROUGH
  • Read the question.
  • Tap your answer.
A bee, a tree and a bird are each one whole living thing. Which level are they?
A family member counts 40 beats in 30 seconds. What is that in beats per minute?
You want a resting pulse. How long should everyone sit still first?
Which tissue makes the heart pump? Type one word.
WHY THIS EXERCISEFrom a bird on a branch to your own wrist, the same ladder of levels is at work.
Draw the three organisms you liked best from the walk. Label each one "organism".
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