Hydroponic Growing Systems Worksheet for 14-Year-Olds | Science & Engineering

Instructions

1. Complete the activities in order. Begin with the easier questions, then apply what you know to design and troubleshoot a hydroponic system.
2. Use the example in each section as a guide. Show your calculations and explain your reasoning.
3. For the design activity, you may sketch on separate paper or describe your design using labeled words and arrows.
4. Remember: hydroponic systems use water and nutrients instead of soil, but plants still need light, oxygen, water, nutrients, and suitable temperatures.
5. Learning goals: By the end of this worksheet, you should be able to identify the parts of a hydroponic system, explain how plants grow without soil, calculate simple water and nutrient needs, and design a safe indoor growing system.

Part 1: Hydroponics Basics

Hydroponics is a method of growing plants without soil. Plant roots receive water, dissolved nutrients, and oxygen through a carefully managed system.

A. Choose the best answer

1. Which item is usually needed in a hydroponic system?

   • A. Soil
   • B. Nutrient solution
   • C. Garden insects
   • D. Compost only

2. What is the main job of a grow light?

   • A. Cool the water
   • B. Provide energy for photosynthesis
   • C. Remove nutrients
   • D. Hold the plant upright

3. Why is oxygen important around plant roots?

   • A. It helps roots carry out respiration.
   • B. It replaces all nutrients.
   • C. It makes the leaves darker.
   • D. It prevents photosynthesis.

4. Which plant is generally a good choice for a beginner's indoor hydroponic garden?

   • A. Lettuce
   • B. Oak tree
   • C. Cornfield
   • D. Large pumpkin vine

5. What is the purpose of a growing medium such as clay pebbles or rockwool?

   • A. To provide physical support for the plant
   • B. To replace the grow light
   • C. To remove all water
   • D. To act as garden soil

B. Match each part to its function

Write the correct letter beside each number.

Functions

• A. Holds the plant and growing medium
• B. Provides water containing dissolved minerals
• C. Provides artificial sunlight
• D. Moves water through the system
• E. Supports roots while allowing water and air to pass through

1. Reservoir: _____
2. Water pump: _____
3. Grow tray or net pot: _____
4. Nutrient solution: _____
5. Growing medium: _____
6. Grow light: _____

Part 2: How Does the System Work?

Complete the flow sequence using these terms: reservoir, pump, roots, grow light, nutrient solution, plant leaves.

Example: Reservoir → pump → __ → roots → plant leaves

1. __ → pump → tubing → grow tray
2. Nutrient solution → __ → roots
3. __ provides energy for photosynthesis.
4. Roots absorb water and nutrients, which move toward the __.
5. After passing through the roots, water may return to the __ in a recirculating system.

Think like a scientist

Why might a plant grow poorly if the pump stops working? Write two possible effects.

Part 3: Compare Growing Methods

Complete the statements with soil, hydroponics, or both.

1. Plants need light: ____
2. Roots grow in a nutrient solution: ____
3. Plants need water: ____
4. Nutrients can be supplied by fertilizer: ____
5. This method can be used indoors: ____
6. Roots are physically supported by a growing medium: ____

Part 4: Plan a Small Indoor System

Imagine you are setting up a hydroponic system for a sunny classroom, bedroom, or kitchen corner. Your system must be safe, affordable, and easy to monitor.

A. Choose your system type

Circle one:

• Kratky method: A passive system with no pump; roots reach a nutrient solution while some roots remain exposed to air.
• Deep-water culture: Plant roots hang in nutrient solution, usually with an air pump or air stone.
• Drip system: A pump sends nutrient solution through tubing to each plant.

My choice: __

B. Design checklist

List the materials you would need. Include at least six items.

C. Label your system

On separate paper, draw or describe a labeled diagram. Include arrows showing the movement of water. Your diagram should include:

• Plant and roots
• Growing medium or net pot
• Reservoir
• Nutrient solution
• Pump, tubing, or air stone if needed
• Grow light or window
• A way for excess water to return to the reservoir, if applicable

Design hint: Keep electrical equipment away from splashing water. Place the light close enough for the plant but not so close that leaves become hot.

Part 5: Data Collection and Observation

Observe a real or imaginary hydroponic plant for five days. Record measurements such as plant height, number of leaves, water level, or root appearance. The first row is an example.

Analyze your data

1. What change did you observe over time?

2. What evidence would show that the plant is healthy?

3. What additional measurement would make your investigation stronger?

Part 6: Practical Calculations

A. Water use

A hydroponic reservoir contains 2,400 mL of water. After four days, it contains 1,850 mL.

1. How much water was used?

Calculation: ____

Answer: ____ mL

2. What was the average amount used per day?

Calculation: ____

Answer: ____ mL per day

3. If the same average use continues for three more days, approximately how much additional water will be needed?

Calculation: ____

Answer: ____ mL

B. Nutrient mixing

A fertilizer label says to add 5 mL of nutrient concentrate for every 1 liter of water.

1. How much concentrate is needed for 3 liters of water?

Answer: ____ mL

2. How much concentrate is needed for 750 mL of water?

Hint: 750 mL = 0.75 L.

Answer: ____ mL

3. Why should a grower follow the label instead of adding as much fertilizer as possible?

Part 7: Troubleshooting Mission

For each problem, choose the most likely cause and suggest one solution.

1. The leaves are pale and growth is slow.

Likely cause: ____

Possible solution: __

2. The roots are brown and have a bad smell.

Likely cause: ____

Possible solution: __

3. The growing medium is dry even though the reservoir is full.

Likely cause: ____

Possible solution: __

4. The leaves have dry brown edges and the light is very close.

Likely cause: ____

Possible solution: __

5. Green slime is growing on the surface of the nutrient solution.

Likely cause: ____

Possible solution: __

Part 8: Real-World Design Challenge

A community center wants fresh lettuce for a weekly cooking class. The room has limited space, a power outlet, and volunteers who can check the plants only every other day.

Your task

Design a system that can grow at least four lettuce plants. Explain your choices.

1. Which hydroponic method would you choose, and why?

2. How would your system provide light?

3. How would you prevent water spills or electrical hazards?

4. What would volunteers check during each visit?

5. What is one possible environmental advantage of growing lettuce indoors without soil?

6. What is one possible disadvantage or resource cost?

Optional Challenge

A system uses 4 watts of electricity for its pump and 36 watts for its grow light. Both run for 12 hours each day.

1. What is the total power use while both are running?

Answer: ____ watts

2. How many watt-hours are used in one day?

Answer: ____ watt-hours

3. If the electricity rate is $0.15 per kilowatt-hour, estimate the daily cost. Hint: 1,000 watt-hours = 1 kilowatt-hour.

Answer: $____ per day

Reflection

Complete the sentence stems.

• One thing I understand about hydroponics is __

  ---

• One question I still have is ____

  ---

• I could use hydroponics in real life to ___

  ---

Answer Key

Part 1

A. Multiple choice

1. B. Nutrient solution
2. B. Provide energy for photosynthesis
3. A. It helps roots carry out respiration.
4. A. Lettuce
5. A. To provide physical support for the plant

B. Matching

1. Reservoir: B
2. Water pump: D
3. Grow tray or net pot: A
4. Nutrient solution: B
5. Growing medium: E
6. Grow light: C

Note: The reservoir holds the nutrient solution, so both the reservoir and nutrient solution connect to function B. The grow tray or net pot holds the plant, matching function A.

Part 2

Example sequence: Reservoir → pump → tubing → roots → plant leaves

1. Reservoir
2. roots
3. Grow light
4. plant leaves
5. reservoir

A stopped pump may prevent roots from receiving water and nutrients. It may also reduce oxygen circulation, depending on the system. The plant could wilt, grow slowly, or die.

Part 3

1. Both
2. Hydroponics
3. Both
4. Both
5. Both
6. Both

Part 4

Answers will vary. A strong answer includes a reasonable system type, at least six useful materials, a clear water path, plant support, light, and safe placement of electrical equipment.

Part 5

Answers will vary. Strong responses identify a pattern using evidence from the data. Possible extra measurements include pH, water temperature, nutrient concentration, root length, light hours, or leaf color.

Part 6

A. Water use

1. 2,400 mL − 1,850 mL = 550 mL
2. 550 mL ÷ 4 days = 137.5 mL per day
3. 137.5 mL × 3 days = 412.5 mL, or approximately 413 mL

B. Nutrient mixing

1. 5 mL × 3 L = 15 mL
2. 5 mL × 0.75 L = 3.75 mL
3. Too much fertilizer can damage roots, interfere with water uptake, create an overly concentrated solution, and harm the plant.

Part 7

Answers may vary if the reasoning is scientifically reasonable.

1. Likely causes include insufficient nutrients or insufficient light. Solutions include checking the nutrient mixture, checking the light schedule, or moving the light closer safely.
2. Likely causes include poor oxygenation, warm stagnant water, or root disease. Solutions include adding aeration, changing the solution, cleaning the system, and removing damaged roots.
3. Likely causes include a blocked tube, failed pump, or poor water flow. Solutions include checking the pump and tubing and making sure the growing medium contacts moisture as designed.
4. Likely cause: light stress or heat from the grow light. Solution: raise the light, reduce intensity, or adjust the light schedule.
5. Likely cause: light reaching nutrient-rich water. Solution: block light from the reservoir, clean the system, and replace the solution if needed.

Part 8

Answers will vary. Strong answers should consider the center's limited space, power outlet, and every-other-day maintenance schedule. A suitable design might use deep-water culture with an air pump or a passive system such as Kratky. The answer should address lighting, spill prevention, electrical safety, monitoring, and environmental trade-offs.

Optional Challenge

1. 4 watts + 36 watts = 40 watts
2. 40 watts × 12 hours = 480 watt-hours per day
3. 480 watt-hours = 0.48 kilowatt-hours. 0.48 × $0.15 = $0.072, or approximately $0.07 per day