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Words you need

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Learning the language:

All sports have their own languages and if a player doesn’t know how to “pick-and-roll”, “give-and-go”, “steal ground”, or “fake bunt” they will not be as successful as those that do. The same is true for science so here are simplified definitions to get you and your “future scientist” started:

Research: As a verb, research is the process of finding information on a topic. The best strategy is to go to a real library and find published books and peer-reviewed journal articles, but in practice most students will start with Google. Research on the internet can be successful if students rely on websites that end in .edu, .gov, and .mil and verify the informational sources. As a noun, research is the product of all that researching. Students will need to document that they researched their topic by showing their research.

Hypothesis is a prediction for the answer to the question proposed by the student researcher. The hypothesis is sometimes called an “educated guess”, but this is misleading. The student should not be guessing, but rather making a logical prediction based on information they know or found during their research. Note that a hypothesis is never “right” or “wrong” (after all, who likes to be wrong?) nor is it “proven” or “disproven”. The correct wording is that the hypothesis was supported or unsupported or the hypothesis was accepted or rejected. Sometimes teachers ask that students put their hypotheses into if…then… statements. Although this should not be required, it is an attempt to help you design the experiment.

A general formula for writing a hypothesis would be: If the independent variable is changed in some way, then the dependent variable will change is some way. For example:

If temperature increases, then viscosity will decrease

Variable (noun) is a part (or factor or item or component) that could have at least two and possibly many different values.

Quantitative Variable is a variable measurable with numbers (e.g., temperature, speed, weight)

Qualitative Variable is a variable describable with adjectives (e.g., hotter, faster, bigger) or categories (e.g., male/female, small/medium/large, red/green/blue)

Independent Variable is a variable manipulated (changed) by the student. It is independent because the student/scientist chooses its values. The independent variable is also called the manipulated variable and can be qualitative (categories) or quantitative (measurement).

Dependent Variable is a variable measured as an outcome of the experiment. The experiment is checking to see if the value of the dependent variable depended on the value of the independent variable. The dependent variable is also called the response variable.
**The most competitive projects usually have quantitative dependent variables.

Constant or controlled variable(s) are any variables that are the same for both the control trials and the experimental trials. These variables are not of interest to the researcher so they are not changed, and consequently these variables are constant. Warning: Students often get confused between a “controlled variable” and the “control” (see below).

Control (noun) is a trial without the independent variable present (or the lowest/highest value of the independent variable depending on the hypothesis). The results of the control trials will be compared to the results from the experimental trials in order to evaluate if there is a difference related to the presence or value of the independent variable.

Replicates: Repeated trials or measurements to show precision of results (i.e., how repeatable is the outcome?). An absolute minimum of 3 are required in a competitive project.

The following are words that are misused:

Theory: Many people use “theory” when they mean “idea”. For example, when someone says “I have a theory about that”, they usually mean they have an idea or a thought or a possible explanation. In science a theory is a well tested, widely supported, explanation of a natural phenomenon accepted as true by most scientists in that field. Examples include the Theory of Island Biogeography, The Theory of Evolution by Natural Selection, and Einstein’s Theory of Relativity. Generally, your science project is not creating a new theory so try not to use “theory” in the project unless you are explaining a specific theory behind the phenomenon you are testing.

Experiment: Along the same lines, many people use “experiment” when they mean “try out”. You may hear someone say “I’m going to experiment with a new recipe tonight”. In contrast, scientists use experiment for a well designed test of a hypothesis.

Significant: Here is another problematic word. We often use significant to mean “meaningful” or “substantial”, but to a scientist, significant specifically means you conducted a statistical evaluation of the data and found mathematical support for or against your hypothesis. At the elementary (and middle) school levels, this is well beyond their grade level and unless the student can explain how the statistics are justified, you should not use the term significant. Warning: if a judge asks a student if “the results were significant”, the judge is evaluating the student’s knowledge of this term.

Prove/Proof: It would be exceptionally rare for a student’s science fair project to prove anything and the idea of “proving” something in science is not the same as “prove” in a court of law. Stay away from this word too. It would be better to state “My results provide evidence for…” or “My results demonstrate that…”

Causation vs. Correlation: With a well designed experiment, it may be tempting to conclude that the change in the independent variable caused the change in the dependent variable. Here again, there are agreed upon rules for claiming causation. For environmental projects with more than one variable measured, be wary of correlation vs. causation.

A creative example of this is the conclusion that eating ice cream causes shark attacks. A survey in most areas would show that as ice cream sales increase, the number of shark attacks increases. The reality is these variables are both related to a third variable (temperature). In the summer, with higher temperatures, both ice cream sales and shark attack cases (because more people go in the water) would be expected to increase independently of each other.

Accurate vs. Precise: These words are often used as synonyms, but have specific meanings in science. Accuracy is a measure of how close the data is to the real value and precision is a measure of how repeatable the measurement is.

12 Responses to Words you need

  1. MRaj

    My 7th grader is doing a science fair project in plant science.
    The idea is to check worm tea prepared from recycled house hold waste worm compost is better for plant growth in hydroponic system compared to the regular nutrient mix (other variable) and water (control – without any nutrients added). She started her worm composting 3 months back. She is planing for 3 replicate in each group and measure the plant length in every 3 days for 20 days. Set up is using
    Control and Experimental group with 9 seeds of black eyed peas and 9 seeds of Okra/ Mung Bean.
    Like that the 3 replicate will have 27 Black eyed peas and 27 Okra/Mung Bean seeds.
    How she can prepare the data table?

    • Dr. Maille Lyons

      I recommend time (in days) gas columns across the top of the table; and rows for each of (1a) control peas, (1b) experimental peas, (2a) control beans, (2b) experimental beans. In each box she can list the plant length measured for each of three replicates (OR the average).

      • MRaj

        Thank you for your reply. Do you think this is a good project for a 7th grader?
        If she is using TTest analysis, she has to do that with Control vs Experiment 1 , Control vs Experiment 2, and Experiment1 vs Experiment2 to identify which is significantly better?

      • MRaj

        My girl’s experiment is progressing. But some how the plant in water shows more growth than NPK solution. Vermicompost is showing better than both of them. What would be the reason for NPK showing less growth than water? She took 3 measurement every 4 days. Now all the seeds attached to the stem is dried or utilized by the plant. No we can expect less growth in water? She has no idea how she can explain the fact like NPK and water is showing almost same growth? If I have your email, I can send you the data sheet.


  2. inferno

    My science fair project was to determine if color affected heat absorbed. I built three popsicle stick houses and I painted one black, one white, and one pink. I set the houses outside on a sunny day and compared the temperatures inside each of the houses after an hour.

    I need qualitative observations. I felt the houses at the end of the experiment. I’m not sure what other observations I should have. Thanks!

    • Dr. Maille Lyons

      Qualitative? Did you notice any condensation? Perhaps also feel the ground beneath? Not sure what else you could have observed….

      FYI: Consider repeating at least 2 more times for proper replication.

  3. Noopur soni

    I m selected for national exhibition, whats the best way to prepare for questions asked by judges & how to deal with it?

  4. christie

    Dr. Mallie Lyons,
    My daughter is doing a tape and surface experiment. She is testing adhesive strength of different tapes on different surfaces. Example: duct tape strength on wood, plastic, and steel measured by weight (how much weight does it take to pull duct tape off the surface ). I am trying to help her with the independent and dependent variables. Also with the controlled/constant variables, for example: would using same weights, surface area, size of bucket be considered controlled variables? Please advise. I don’t want to tell her wrong. Thanks so much.

    • Dr. Maille Lyons

      Independent is what she manipulates: she has 2 – type of tape and surface
      Dependent is what she measures: weight needed to dislodge
      Controlled/Constants – everything else that stays the same: temperature, amount of tape (i.e. tape to surface ratio), time tape stuck on surface before test, weights, etc.

      The control is tricky… it will depend on her hypothesis/question. It should be the combination that she predicts will be the best (or worst – her choice) because the changes and corresponding results will be compared to her initial predictions.

      • christie

        I understand everything except the control. Her hypothesis is that she predicts that duct tape will hold the most weight before pulling off its surface and that duct tape will have the strongest adhesion to a plastic surface. Purpose is to compare tape adhesive strength and if surface affects tapes adhesion. What do you think the control will be in her experiment? Thanks for all your help.

        • Dr. Maille Lyons

          Why did she pick Duct tape instead of the other types of tape? And Why did she decide the strongest adhesion will be to plastic instead of wood or steel or other surfaces? If I were a science fair judge (and I am 😉 this would be my first question. There is no right or wrong answer – just make sure she can articulate why she thought that was the “best” combo.

          So since she decided that Duct tape and plastic are the best combo… then changes to that combo should result in lower adhesion (less weight to tear it off).

          Then her hypothesis is really something like… If the surface type and/or the tape type changes, then the adhesion will decrease.

          That makes the Duct tape- Plastic combo the control because she will compare all the other results to it to determine if indeed it had the best adhesion (all other combos will need to be lower to accept the hypothesis; otherwise the hypothesis will be rejected).

          She should be planning on testing all of her types of tape on all of her types of surfaces so that she will ultimately have a grid of results (for each type of tape selected – what were the results and for each surface selected what were the results); she will have several bar graphs to make/present.

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