Question

david’s dilemma
david noticed that grass in the driveway where his brother washed his car was not nearly as thick as the rest of the lawn and in some places it had died. david wondered if the detergent his brother was using was causing the grass to die so he decided to conduct an experiment.
david went out and bought some grass seed from the local lawn and garden store and a bottle of the same kind of detergent that his brother used to wash the car.
using the grass seed, the detergent and david’s question, design an experiment to see if the detergent was killing the grass as david suspected.
problem:
hypothesis:
independent variable:
dependent variable:
constants:
controls:
materials:
procedure: (use the back if you need extra room)
data table: (draw a table that would allow you to collect the data for this experiment – be sure to name your columns and rows)

Explanation:

Problem:

Does the detergent used to wash the car kill the grass?

Hypothesis:

The detergent used to wash the car will kill the grass (or will have a negative effect on grass growth).

Independent Variable:

Presence/absence of the detergent (or application of detergent)

Dependent Variable:

Grass growth (or health of the grass, e.g., whether it dies, how thick it is, etc.)

Constants:

• Type of grass seed used
• Amount of water given to each grass patch
• Amount of sunlight each grass patch receives
• Temperature conditions
• Soil type (if using soil)

Controls:

A patch of grass that does not receive the detergent (to compare with the patch that does receive the detergent)

Materials:

• Grass seed
• Detergent (the one used by David’s brother)
• Containers/pots (or marked areas in the lawn)
• Soil (if needed)
• Watering can
• Ruler (to measure grass growth, optional)

Procedure:

1. Prepare two identical containers (or mark two identical areas in the lawn) with the same soil, grass seed, and initial conditions (water, sunlight, etc.).
2. Label one container/area as the “Control Group” and the other as the “Experimental Group.”
3. Plant the same amount of grass seed in both containers/areas.
4. Water both groups with the same amount of water regularly.
5. Apply the detergent (according to the car - washing concentration, e.g., mix as used for washing the car) to the “Experimental Group” at the same time intervals as the car was washed. Do not apply detergent to the “Control Group.”
6. Observe and record the growth/health of the grass in both groups over a set period (e.g., 2 weeks, 1 month). Record observations like grass height, color, density, or whether it dies.

Data Table:

Group	Initial Grass Condition (Day 0)	Grass Condition (Day 7)	Grass Condition (Day 14)	Grass Condition (Day 21)	...
Experimental

(Note: “Grass Condition” can be described as height (in cm), color (e.g., green, yellow, brown), density (e.g., sparse, dense), or a simple “alive”/“dead” notation depending on the level of detail desired.)

Answer:

Problem:

Does the detergent used to wash the car kill the grass?

Hypothesis:

The detergent used to wash the car will kill the grass (or will have a negative effect on grass growth).

Independent Variable:

Presence/absence of the detergent (or application of detergent)

Dependent Variable:

Grass growth (or health of the grass, e.g., whether it dies, how thick it is, etc.)

Constants:

• Type of grass seed used
• Amount of water given to each grass patch
• Amount of sunlight each grass patch receives
• Temperature conditions
• Soil type (if using soil)

Controls:

A patch of grass that does not receive the detergent (to compare with the patch that does receive the detergent)

Materials:

• Grass seed
• Detergent (the one used by David’s brother)
• Containers/pots (or marked areas in the lawn)
• Soil (if needed)
• Watering can
• Ruler (to measure grass growth, optional)

Procedure:

1. Prepare two identical containers (or mark two identical areas in the lawn) with the same soil, grass seed, and initial conditions (water, sunlight, etc.).
2. Label one container/area as the “Control Group” and the other as the “Experimental Group.”
3. Plant the same amount of grass seed in both containers/areas.
4. Water both groups with the same amount of water regularly.
5. Apply the detergent (according to the car - washing concentration, e.g., mix as used for washing the car) to the “Experimental Group” at the same time intervals as the car was washed. Do not apply detergent to the “Control Group.”
6. Observe and record the growth/health of the grass in both groups over a set period (e.g., 2 weeks, 1 month). Record observations like grass height, color, density, or whether it dies.

Data Table:

Group	Initial Grass Condition (Day 0)	Grass Condition (Day 7)	Grass Condition (Day 14)	Grass Condition (Day 21)	...
Experimental

(Note: “Grass Condition” can be described as height (in cm), color (e.g., green, yellow, brown), density (e.g., sparse, dense), or a simple “alive”/“dead” notation depending on the level of detail desired.)