Controlled Experiment Example

Wondering how to set up a controlled experiment? Look here!

  1. Problem
    • Do seeds germinate faster if fertilizer is applied?
  2. Hypothesis
    • If fertilizer is applied to the soil, then the seeds will germinate faster
  3. Materials Needed
    • Seeds  Water
    • Soil  Sunlight
    • Seeding tray  One brand/type of fertilizer
  4. Constants
    • Type of seed
    • Type of Soil
    • Source of water
    • Amount/frequency of watering
    • Amount of sunlight
    • Temperature
    • Dew point
  5. Control
    • The seedling without fertilizer will be the control for this experiment
  6. Independent Variables
    • The fertilizer added to Plants B and D is the only independent variable for this experiment
  7. Dependant Variables
    • The primary dependant variable for this experiment will be the time for the seedlings to germinate. Other variables which may be monitored include the height and fruitfulness of each plant.
  8. Procedure
    1. Pour 1 cup of soil into one seeding tray; repeat three more times
      1. Measure out 1 cup of fertilizer, and equally divide it into two separate seeding trays, already filled with soil
      2. Mix the fertilizer into the soil
      3. Take four seeds, and bury them ½ inch below the surface of the soil. One seed should be sewn in each tray that has soil in it.
      4. Mark the seedling trays as Plant A, B, C, or D. Plants A and C are the controls, and have no fertilizer. Plants B and D are the plants that have fertilizer.
      5. Place the seedling trays in the same room, and in the same area in that room. There should be a uniform amount of sunlight. Temperature and dew point in the room should be constant.
      6. Water each seedling ½ cup of water
      7. Record measurements for each seedling under day one (they will all be zero inches)
      8. Every day, each seedling tray should be watered with ½ cup of water. After watering, measure each seedling to see if it has grown. Measure from the surface of the soil to the tallest part of the plant (in inches).
      9. Continue watering and measuring every day until the plants die
  9. Tools for Data Recording

Experimental Data Collection

  Day # 1 2 3 4 5 6 7 8 9 10
Plant Plant A                    
Height Plant B                    
in Plant C                    
Inches Plant D                    
Legend: Plant A no fertilizer
  Plant B Fertilizer
  Plant C no fertilizer
  Plant D Fertilizer

 Image by author

  1. Analysis and Conclusion

Based on data collected, the experimenter will conclude as to whether or not the fertilizer added to plants B and D accelerated their growth. If the fertilizer had any impact, Plants B and D will consistently have greater height measurements than Plants A and C throughout the experiment. The measurements should be plotted into a line graph, which will then illustrate the height of plants grown with no fertilizer versus plants grown with fertilizer. While this is a rather simple experiment, there are multiple possibilities for human error to have an undesirable effect on the results. Planting the seeds too far into the soil or over watering the seedlings may prevent the plants from growing at all. Therefore, it would be important for anyone undertaking this experiment to carefully read the planting instructions on the seed packaging. Too much fertilizer mixed into the soil may be toxic to the seedlings, so the experimenter should also pay close attention to the directions on the package of fertilizer. It is important to eliminate any other possible variables, such as temperate, dew point, and amount of sunlight so that it is possible to conclude that the fertilizer (or lack of fertilizer) was the sole contributor to faster (or slower) germination.

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13 Responses to “Controlled Experiment Example”
  1. Atif Says...

    On June 6, 2009 at 11:55 am

    Hey Thanks for posting this article. I had an exit project on this and I think , I dont need to do the project for you gave me such a good example. Thanks

  2. rick Says...

    On July 17, 2009 at 11:05 am

    ei, thanks for the article!

  3. Greg Says...

    On May 6, 2010 at 10:33 pm

    Could you tell me how long it took for this experiment? My son has approx. 4 weeks before it is due.

  4. ciera Says...

    On September 14, 2010 at 7:38 pm


  5. Brianna Says...

    On October 7, 2010 at 9:13 pm

    Thanks for the articl it really helps!!

  6. babes Says...

    On January 9, 2011 at 8:56 pm

    tytyty i had a 7th grade controlled experiment example to do and i saw this and i was happy since i finally had one to do :) ))))

  7. Jane Says...

    On February 3, 2011 at 1:22 am

    helpful fo rmy kid’s 5th grade homework for science, thxs!

  8. pinks Says...

    On February 27, 2011 at 4:21 pm

    THX for the help wit my science fair <333333333333333333333333333333333333333333333333333333333333333333333333 U!

  9. Joe Says...

    On October 11, 2011 at 11:06 pm

    Great Great example. Has everything you need to pass a project that is a controlled experiment. Alot more useful than other websites I had visited. Great work.

  10. greensandbluesbabesss Says...

    On February 19, 2012 at 9:02 pm

    ummmmmmmmmmmmmm it was ok but i ummm just needed an example but i might do this one…idk hahaha i had one planned hahah dont know if its good haha im not looking for an A+ though a B- or B+ works too or an A- or an A+ but i dont want to be known as super smart you know i want to be average haha bye thanks i guess

  11. Nick Says...

    On September 26, 2012 at 3:11 pm

    This is an amazing help thank you so much!

  12. Nick Says...

    On September 26, 2012 at 3:12 pm

    This is an amazing help thank you so much.

  13. Trinity Woodson Says...

    On January 5, 2013 at 1:34 pm

    What were the measurements, type of seeds, type of fertilizer, and results?

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