Design a Sustainable Garden
Plan, calculate, and pitch a school garden that grows food sustainably.
Subjects Connected
Science
Plant needs, ecosystems, composting, native vs introduced species
Maths
Area, perimeter, volume of soil, budgeting with money
English
Persuasive writing, formal proposals, presenting arguments
Inspired by Finnish phenomenon-based learning: "How can we grow food sustainably?"
The Big Question
"How can we grow food sustainably in our school?"
In this project, you will design a garden, calculate what you need, understand the science of growing, and write a persuasive proposal to make it happen.
Science: What Plants Need
The Five Things Every Plant Needs
For a garden to thrive, every plant needs these five essential things:
Sunlight
Energy for photosynthesis
Water
Absorbed through roots
Soil
Nutrients and support
Air
CO2 for photosynthesis
Warmth
Right temperature range
Composting: Nature's Recycling
Composting turns food scraps and garden waste into rich soil. Micro-organisms break down organic matter, creating humus — dark, nutrient-rich material that helps plants grow. A sustainable garden creates its own compost instead of buying fertiliser.
Good for Compost
- Fruit and vegetable scraps
- Leaves and grass cuttings
- Egg shells
- Cardboard and newspaper
Not for Compost
- Meat or dairy products
- Cooked food
- Plastic or metal
- Diseased plants
Native vs Introduced Species
Native plants are species that naturally grow in your area. They are adapted to local conditions and support local wildlife (bees, butterflies, birds). Introduced species come from other countries — some are fine, but some can become invasive and crowd out native plants.
Think About It (Claim-Support-Question)
Consider the claim: "A school garden with only native plants is better than one with a mix of native and introduced species."
- Claim: Do you agree or disagree? Take a position.
- Support: What evidence supports your view?
- Question: What would you need to find out to be more certain?
Maths: Measuring and Budgeting
Calculating Area and Perimeter
To plan your garden beds, you need to calculate how much space you have and how much material to buy.
Example: A Rectangular Garden Bed
Area = length x width = 4m x 2m = 8 m² (square metres)
Perimeter = 2 x (length + width) = 2 x (4 + 2) = 2 x 6 = 12 m
The area tells you how much soil you need. The perimeter tells you how much edging material to buy.
Calculating Soil Needed
Garden beds need to be filled with soil. If the bed is 20cm deep:
Volume = length x width x depth
= 4m x 2m x 0.2m = 1.6 m³ (cubic metres)
Soil is often sold in 25-litre bags. 1 m³ = 1,000 litres.
1.6 m³ = 1,600 litres. That is 1,600 ÷ 25 = 64 bags of soil.
Budgeting for the Garden
Every project has a budget. Here are some typical costs:
| Item | Cost per Unit | Quantity | Total |
|---|---|---|---|
| Timber edging (per metre) | $8 | 12m | $96 |
| Soil (25L bag) | $6 | 64 bags | $384 |
| Seedlings (punnet of 6) | $4 | 8 punnets | $32 |
| Mulch (large bag) | $10 | 4 bags | $40 |
| Watering can | $15 | 2 | $30 |
| TOTAL | $582 | ||
Think About It (Tug of War)
The budget is $582, but the school only has $400 to spend.
- What could you cut or reduce to bring the cost down?
- Could you get any materials for free? How?
- What are the trade-offs of making the garden smaller?
English: Writing a Persuasive Proposal
Your mission: convince the school principal to approve your garden plan. A persuasive proposal uses facts, reasons, and emotion to win someone over.
Structure of a Persuasive Proposal
1. Introduction
State your proposal clearly. What do you want to do and why?
2. Reasons (with evidence)
Give 3 strong reasons, each supported by a fact or example. Use your science and maths knowledge!
3. Address Concerns
Anticipate objections (cost, maintenance, space) and explain how you will handle them.
4. Conclusion
Restate your case with a strong closing sentence. End with a call to action.
Persuasive Language Toolkit
Sentence Starters:
- "Research clearly shows that..."
- "It is essential that we..."
- "Not only would this... but it would also..."
- "Furthermore..."
Powerful Words:
- sustainable, beneficial, valuable
- community, responsibility, opportunity
- evidence, proven, significant
- investment, long-term, impact
Think About It (Step Inside)
Step inside the shoes of the school principal reading your proposal.
- What questions would they ask?
- What concerns would they have?
- What would make them say "yes"?
Key Vocabulary
Photosynthesis
The process plants use to convert sunlight, water, and CO2 into food (glucose) and oxygen.
Ecosystem
A community of living things (plants, animals, insects) and their environment, all interacting together.
Area
The amount of space inside a flat shape, measured in square units (m²).
Perimeter
The total distance around the outside of a shape.
Persuasive
Writing or speech designed to convince someone to agree with your point of view.
Sustainable
Done in a way that can continue for a long time without harming the environment.
Activities & Investigations
Garden Site Survey (Science + Maths)
Walk around your school grounds (or garden at home). Identify the best spot for a garden bed. Consider: How much sunlight does it get? Is there access to water? Measure the available space and calculate the area.
Design Your Garden Plan (Maths)
Draw a scale plan of your garden on graph paper (1 square = 20cm). Include at least 2 garden beds, a compost area, and a path. Calculate the area and perimeter of each bed, and the total soil needed.
Plant Research (Science)
Research 6 plants that would grow well in your area. For each plant, note: What does it need? When should it be planted? Is it native or introduced? How long until harvest?
Write Your Proposal (English + All Subjects)
Write a persuasive proposal to the principal. Include your garden plan, budget table, plant selections, and at least 3 strong reasons why the school should build this garden. Use data from your maths calculations as evidence.
Knowledge Check
Test your understanding across all three subjects.
Question 1 Maths
A rectangular garden bed is 5 metres long and 3 metres wide. What is its area?
Question 2 Science
Which of these should NOT go in a compost bin?
Question 3 Maths
Soil costs $6 per bag and you need 40 bags. Seedlings cost $4 per punnet and you need 6 punnets. What is the total cost?
Question 4 Science
Which of these is NOT something plants need to grow?
Question 5 English
Which sentence is most persuasive for a garden proposal?
Key Concepts Summary
- ● Science: Plants need sunlight, water, soil, air, and warmth. Composting recycles organic waste into nutrient-rich soil. Native plants support local ecosystems.
- ● Maths: Area = length x width. Perimeter = total distance around. Volume = length x width x depth. Budgeting means tracking costs and staying within a limit.
- ● English: Persuasive writing uses evidence, strong reasons, and addresses counter-arguments. A good proposal has a clear structure and specific data.
- ● Connection: Real-world projects require all these skills together — understanding the science, doing the maths, and communicating the plan clearly.