Lesson 7 of 8 · Crosscutting Concepts
Experiment⭐ 30 XPSystems Have Inputs, Outputs and Limits
Crosscutting Concepts.
🎯 Your mission
Predict it first. Then prove yourself right (or wrong).
⚡ The twist
Nature loves to surprise the careful watcher.
Mind = Blown
🔬 The more you look, the more nature shows you.
Make a hypothesis first
Before you start: write down what you think will happen, and why.
What You'll Learn
Treat anything as a system and ask three questions: what goes in, what comes out, and what limits the rate? A plant's growth is limited by whichever of light, water, carbon dioxide or nutrients is scarcest — never by all of them at once.
Key Words
Tap a word to see its definition.
Materials Needed
- cress seeds
- four pots
- soil
- water
- cardboard box
- ruler
Safety First
- Wash hands after handling soil and do not eat anything grown in the experiment.
Steps
Read the explanation above and note the two key terms before you start.
Grow cress under four conditions, each short of a different input. Measure growth after a week, identify the limiting factor in each pot, and predict what would happen if you fixed only one.
Record what actually happened, including anything that did not match what you expected.
Write a conclusion that answers the question this lesson opened with, and state your uncertainty.
Check Your Understanding
Question 1
1 of 2A limiting factor is the input that is:
Where you see this in real life
This shows up in your everyday life more than you'd think.
Stretch Challenge
Try this in real life this week.
Try one experiment in real life this week — even a tiny one.
For the dinner table
“What's the most surprising thing you learned today?”
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Systems Have Inputs, Outputs and Limits
Predict it first. Then prove yourself right (or wrong).
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