Plant Investigation:

Purpose of the Investigation: How do environmental factors affect the

height of bean plants?

Your Goals: Develop a hypothesis that answers a question related to

the purpose of the experiment using an If…then…because…. statement.

Design an investigation to study how an environmental factor can affect plant height.

Construct a data table documenting what you did to your plant each day and what you observed.

Construct a data table documenting the daily height of your plants once they start growing.

Construct a graph comparing your plants height at the end of the investigation.

Step 1: Ask a Question The first step in an experiment is to ask a

question. For a question to be answered scientifically, it

must be clear testable measurable controllable

Question for Investigation:

How does________________________ the independent variable (to be determined)

affect the height of bean plants? the dependent variable

Step 2: Determine Variables

There are 3 kinds of variables that you must account for in an experiment. Independent variable Dependent variable Controlled variables

The independent variable is what you change in the investigation. For example, if you are testing which type of

fertilizer causes the plant to grow taller, your independent variable is type of fertilizer.

In this case, the only thing that will be different in the investigation is the type of fertilizer.

Where you put the plant and how much water you give it must stay the same for both plants.

Examples of independent variables: Amount of sunlight Amount of fertilizer Amount of water Type of fertilizer Type of container Size of container

Fertilizer vs No Fertilizer Greenhouse vs Classroom Sunlight vs No Sunlight Rotating the plant Type of planting medium Type of water

The dependent variable is what you measure in the investigation.

In this investigation: the dependent

variable is the height of the bean plant.

each groups dependent variable will be the same.

Any other conditions in the experiment are called controlled variables (things you aren’t changing).

light exposure type of soil amount of water type of water amount of fertilizer type of fertilizer size of container type of container

Note: You must keep the controlled variables the same for all the plants in the experiment.

Depending on the investigation one group’s independent variable, might be another group’s controlled variable. Example: Mark’s group’s independent variable is amount

of water so the amount of water in each plant will be different but the amount of fertilizer will be the same.

Kelly’s group’s independent variable is type of fertilizer so the amount of fertilizer in each plant will be different but the amount of water will be the same.

Background Information What information is already known that may

be important to consider as you work on this investigation?

For this plant investigation you can use pages 110-117 and 140 –149 in the plant book as your source.

Step 3: Form a Hypothesis The next step in an experiment is to come up with a

hypothesis using an IF – THEN – BECAUSE statement.

This is what you think the answer to the investigation question is. For example: Question: How does the amount of sunlight affect the

height of bean plants? Hypothesis: If plant A gets more sunlight than plant B,

then plant A will grow taller because the more sunlight plants get the taller they will grow.

Step 4: Create a Materials List

List all of the materials and supplies you will need for the investigation.

Add to the list as you develop your procedure.

Step 5: Design a Procedure Each step in the procedure must be numbered

and begin on a separate line. The procedure must be sequential and describe

exactly what you will do to perform the investigation.

The instructions for each step need to be written clearly and completely enough so that someone else could easily repeat your investigation.

Step 5: Design a Procedure Include the observations (qualitative data) and the

metric measurements (quantitative data) you will make. Qualitative data: include words and descriptions of any

changes you see. Example: such dryness or dampness of soil

Quantitative data: write down what you observed in your investigation using numbers and metric measurements. Example: Plant height measurements in centimeters.

Example of a Poor Procedure Step 1: Gather materials from the list. Step 2: Poke holes in the cups to drain water. Step 4: Put dirt in the cups. Step 5: Plant the seeds. Step 6: Add water. Step 7: Put the cup in front of the window.

Improving a Poor Procedure Step 1: Gather materials from the list. Step 2: Poke holes in the cups to drain water.

Where? How many? How big? Step 3: Put dirt in the cups.

How full? What kind? Step 4: Plant the seeds.

How many? How deep? Step 5: Add water.

How much? How often? What specific days? Step 6: Put the cup in front of the window.

Things to consider: How will you label your plants so you can tell them apart?

If everybody labels them “Plant A” and “Plant B” it can be confusing.

How will the water drain from your plant? What days will you water your plants?

You need to be specific. For example: Give plant #1 20 mL of water on Monday and

Friday.

Don’t remove your plant from its environment. Observe and care for your plants in the same place each day. This means you take the water and/or fertilizer to the plant and

you measure it where it is.

Good Procedure Step 1: Gather materials. Step 2: Poke four holes in the bottom of each cup evenly

spaced so excess water will drain. Note: If the containers have drain holes skip this step.

Step 3: Clearly label each cup. Note: You many want to use your initials and write watering

directions on each cup so they will not get mixed up. Step 4: Add soil to each cup and pack the soil down until it

is 2 cm from the top.

Good Procedure cont… Step 5: Plant 2 seeds ______ cm deep.

Check package for planting depth. Step 6: Give plant CMB #1 20 mL of water on Monday

and Friday. Give plant CMB #2 20 ml of water and 10 ml of liquid fertilizer every Monday and Friday.

Step 7: Put the cups in front of the window.

Observations: Create two data tables. Create a graph: see book page 192 for

examples.

Data Table #1 Record what you do to your plant each day and what you

observe (qualitative data). Have the person that cares for the plant initial each day they

cared for the plant.

Day Plant A Plant B

Thursday 2/24 Soil is wet. Soil is dry

Friday. 2/25 20 ml of water

Soil is wet. Plant is breaking through the soil. CB

20 ml water and

10 ml of fertilizer

Soil is damp. TH

Weekend -------------- ---------------

Data Table #2 Record your plant height each day in centimeters

(quantitative data).

Day Plant A Plant B

Feb 22 Start Start

Feb 23 0 cm 0 cm

Feb 24 0 cm 0 cm

You must follow your procedure exactly. The only variable that can be changed is the

independent variable. Everything else you do to your plants needs to be the

same. If your plant starts to die because you didn’t water it

enough or you watered it too much it’s okay because this is how you learn.

If there is time stop the investigation, note your errors,

rewrite your procedure and start a new trial.

Bar Graph: Create a bar graph to record your plants’ height. Include a title for your graph, and label the

vertical and horizontal axis.

Conclusion: Your conclusion sums up what you have

learned from the experiment. Your conclusion explains in detail whether or

not you think the data you collected proves or disproves your hypothesis and why.

Include the following in your conclusion: Purpose of the investigation. Restate your hypothesis and explain whether

your hypothesis was correct or not. List any sources of error. Explain how your experiment could be improved

if someone were to attempt it again.

Claim, Evidence, Reasoning: Claim: a statement or conclusion that answers the original

question.

Evidence: scientific data that supports your claim. A good explanation only uses data that supports the claim in answer to the original question. When selecting your data to use as evidence consider both whether it is appropriate to support the claim and whether you have enough data to support your claim.

Reasoning: makes the connection between the claim and the evidence. Reasoning is a justification that shows why the data counts as evidence to support the claim and includes appropriate scientific principles (the scientific background information that allowed you to make the connection between claim and evidence.)

Folder Name of Investigation Your group member names and hour.