Lesson 2: Engineering Water Exchange and Plant Integration
Duration of Days: 4
Lesson Objective
Students will implement a classroom grow system connected to the tank and establish functional water exchange.
How does water physically move between zones?
What flow rate supports nutrient delivery?
How do we prevent clogging?
Pump
Gravity return
Flow rate
Drainage
Media bed
HS-ETS1-3
Evaluate solutions based on criteria and trade-offs.
SEP – Planning and Carrying Out Investigations
Students analyze cause and effect in system modifications.
Day 1 – Crop Exposure and Classification
Students are introduced to several plant categories:
Leafy greens
Herbs
Fruiting plants
They research and record:
Growth time
Nutrient demand
Root size
Light requirements
Harvest cycle
Class discussion centers on a key contrast:
Fast-growing, low nutrient plants versus slow-growing, high demand plants.
Purpose of Day 1
Move from aesthetic plant thinking to functional agricultural reasoning.
Day 2 – System Compatibility Analysis
Students revisit current tank data:
Current nitrate levels
Estimated fish load
Available grow space
Lighting limitations
Students answer:
Given our nitrate production, which plant type makes sense?
Would high-demand crops overwhelm this system?
Would low-demand crops leave excess nitrate unused?
Students create a comparison chart linking:
Nitrate production ? Plant demand ? System fit
Purpose of Day 2
Students connect plant biology to system data and carrying capacity.
Day 3 – Justification and Proposal
Students choose plant species for integration.
They must justify:
Why this plant fits our nitrate production
Why root mass will not clog system
Why growth rate aligns with monitoring timeline
What trade-offs they accept
Students submit a written crop selection proposal.
Optional Day 4 – Yield Forecasting
Students estimate:
Projected plant growth over 2–3 weeks
How biomass might affect nitrate reduction
They make a qualitative prediction:
Will nitrate decline quickly, gradually, or plateau?
Purpose of Optional Day
Introduce predictive reasoning before comparative experiment.
DOK Level
DOK 2
Compare plant characteristics and identify system constraints.
DOK 3
Justify plant selection using system data and capacity reasoning.
Approaches DOK 4
When students forecast impact on nitrate cycling.
Urban farms select crops based on space and nutrient availability.
Communities facing food insecurity rely on fast-harvest greens.
Farmers must balance yield with system sustainability.
All plants grow equally well in aquaponics.
Faster growth is always better.
More plant mass automatically solves nitrate problems.
Decorative plants function the same as edible crops.
Provide plant comparison templates.
Offer sentence stems for justification.
Allow visual diagram linking nitrate to plant uptake.
Challenge advanced students to compare nutrient density across crops.
Plant Selection Proposal
Students submit a written justification explaining compatibility, trade-offs, and projected impact on system balance.