What Do These Science Project Terms Mean?

science terms and definitions

Kid (and Mom) Friendly Definitions to Science Project Terms

You’ll probably run across a lot of new vocabulary while doing a science project. Some of the things below will be required for your science project, and others will not. We recommend you print this page and highlight the things your teacher wants you to do.

To help explain some of the unfamiliar terms, we’re going to refer to the following experiment.

“What type of fertilizer produces the most plant growth?”

Project summary: A group of plants of the exact same height is divided into five groups. Each of four groups is given a different type of fertilizer. The fifth group is given only water. At the end of one month, plants are measured.

Science Project Proposal – This is a short description of your science project. It needs to include your purpose, hypothesis, materials, and procedure. Your teacher may also want you to list the variables, and give places where you will do research. Turn it in as early as you can, in case it is rejected.

Purpose (Problem) - The purpose is what your project hopes to find out or prove. It’s the ‘big question’. What is your goal? What are you trying to test? That’s your purpose, sometimes stated as a problem.
The purpose of our science project is to find out, “What type of fertilizer produces the most plant growth?”

Hypothesis - An hypothesis is simply an educated guess about what will happen in your experiment. To form your hypothesis, take all the information you know about your science project question, and use it to predict what you think will happen. It doesn’t matter if you’re right or wrong; that’s what the experiment will tell you! In our experiment, the hypothesis will be, “I think that …. will make plants grow the highest.” Use what you know about fertilizer, advertisements, comments from a gardener you know, or personal experience to formulate your hypothesis.

Materials – This is a detailed list of exactly what you used (or plan to use) in your experiment:

  • Four types of liquid houseplant fertilizer -Peters Professional® All Purpose Plant Food, Spectrum® Colorburst Plant Food, Osmocote® Indoor Outdoor Plant Food, and Miracle-Gro® All Purpose Plant Food
  • 20 identical terra cotta pots filled with potting soil
  • 20 bush bean plants of identical height
  • Water
  • Ruler

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Procedure – A step by step description of how to do your experiment. Another person should be able to do your experiment again, just by following your procedure.

Variables – When doing a science experiment, there are things that you, as the scientist, control to make sure your test results are dependable:

  • Independent Variable – The independent variable is the thing that you change in the experiment. All the other things in your experiment should stay the same. For example, in our experiment the independent variable is the type of fertilizer. We’ll use the same kind of pot, soil, and plant. We’ll have the plants get the same amount of light and stay in the same room at the same temperature. We’ll add the same amount of water. The only thing that will change is the kind of fertilizer.
  • Dependent Variable – The dependent variable is the thing that changes because of the independent variable. For us, that would be the height of the plant. The height of the plant changed because we changed the type of fertilizer.
  • Control – The Control is the group in which nothing changes at all. In the fertilizer experiment, that would be the group of plants that only was given water with no fertilizer.

Metric Measurements – Sometimes teachers require students to do all measurements in metrics, which is a decimal system of measurement based on:

  • The Meter – measures length. The English system uses yards, feet, and inches. One meter equals 39.37 inches.
  • The Kilogram – measures mass, or the amount of matter present. It’s not the same thing, but you can relate mass to weight. The English system measures mass in pounds and ounces. A pound is 2.2 kilograms.
  • The Liter – measures capacity or volume. The English system uses gallons, quarts, teaspoons, tablespoons, ounces – and 2 liter bottles! An American gallon is 3.8 liters.

If you have to convert English measurements to Metrics, go to Google and type in “convert 2 inches to meters”, or whatever you need to convert. Sometimes, you don’t even have to think!

science project logScience Log – A journal of what happened in your experiment, from day to day or minute to minute. In our experiment, an entry might read, “On day five, we noticed that the plants with fertilizer had really started getting taller than the control that was only getting water.” Or…”On day seven, we noticed that the plants getting … brand fertilizer had started to wilt a bit.”

If you are doing one of our 24 Hour Science Projects, your log will record changes at much more frequent intervals. You will often need to keep a graph of data in your log. In our experiment, the graph might look like the one to the right. Obviously, the graph would extend to include all the days. You would measure and fill in the height of each plant daily.

Graph – The words chart and graph are used interchangeably. We use the word “graph” for a numbers placed on a grid (or spreadsheet) like the one below.
chart for a science board

Chart – A chart arranges the information (data) from your experiment visually, so you can see it. Look at the chart below, which gives the average height.

average height of plant

Abstract – Some science fairs require an abstract, which is a brief but complete summary of your project. It probably should not be more than 250 words.

Data – Data means information. It’s plural, so the absolute correct usage would be “The data show us that…” (Actually, one piece of data is datum, which you really don’t need to know unless you’re taking Latin or have an extremely pedantic teacher.) Your data will most often be in numbers, although if you were a zoologist, your data might be observations about the feeding habits of anteaters. The measurements of the plant height (the numbers in the graph) give the data for our experiment.

Analysis – When you explain your data and observations, you are giving an analysis. What have you learned? Why did you get the results you did? What did the experiment prove? And, most important, was your hypothesis correct? The analysis for the fertilizer experiment would begin “We discovered that the Miracle Gro produced the most plant growth. While water produced the least growth overall, it is worth noting that two of the plants died after having been added Peters fertilizer. Our hypothesis was disproved, as we thought the Peters fertilizer would produce the tallest plants.

Conclusion – Answer your problem/purpose statement. What does it all add up to? What did you learn from your project?

Application - What questions come up as a result of your experiment? What else would you like to know? If you did this project again, what would you change? How can this project help in real life? While we discovered which plants grew tallest, we didn’t test which plants had the most flowers, and would give the most fruit. This would be what we would like to see answered in our next experiment. We have learned, however, that it is important to use a fertilizer, and we have learned some of the best brands.


If you haven’t done so yet, take a look at all the projects we have at 24 Hour Science Projects. Our project guides take you step by step through the steps of a science project in the same, kid (and mom!) friendly language as these definitions.

About sciencemom

My name is Kayla Fay, and my husband and I have four sons. We’ve turned in over 25 science projects. We remember the disappointment of having an experiment fail. We know how frustrating it is to search for a good project at the last minute. The five 24 Hour Science Projects have experiments our sons have completed successfully. The project guides will help you have the same success with your science experiment!

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