Identifying Variables in a Science Experiment

Typically in a unit on the scientific method, the biggest hurdle for students is understanding and identifying the different types of variables in a science investigation or experiment.

A variable is anything that could change during an experiment. This post will walk through the different variables. Also be sure to check out a a future post on writing and understanding a hypothesis as that will also help gain a deeper understanding of this concept.

Independent Variable - Also called the manipulated variable. This is what the person doing the experiment changes or what is being tested or the attempted solution to a problem.

Ex. 1 - A person is experimenting with how fast sugar dissolves in different temperatures of water. The person has three cups of water at three different temperatures. The independent variable is the different temperatures of water.

Ex. 2 - A person is testing different stain removers on grass stains. The different stain removers would be the independent variable.

Ex. 3 - You are having trouble waking up in the morning (major problem) so you decide to find a solution. You try different types of music as your wake up song in the morning. The independent variable would be the different types of music.

What do you think? Make sense? Let's move to dependent variable.

Dependent Variable - Also called the responding variable because it responds or depends on the independent variable (rock and roll song with a major drum solo, you wake up and get to school on time, light classical music, sleep till noon.) One of the best ways to identify the dependent variable is to find what is being measured or observed. In other words, you are looking for the results.

Ex. 1 - In example one, a person is experimenting with how fast sugar dissolves in different temperatures of water. The time that sugar dissolves depends on the temperature of the water. The time that the sugar dissolves is also what is being measured. This means that the dependent variable  is the time the sugar dissolves.

Ex. 2 - In example two, a person is testing different stain removers on grass stains. How clean the stain is or in other words how much of the grass stain is gone is the dependent variable.

Ex. 3 - In example three, the dependent variable would be the time it takes you to wake up in response to the type of music being played on your alarm clock.

Good review so far? One more variable to go.

Control / Constant  / Standardized Variables - Variables that should stay the same in order to have a "fair" experiment.

Ex. 1 - Sugar / water experiment. Control variables would include the type of sugar, the amount of water, the cup used. These are all variables that should be the same in every trial.

Ex. 2 - Stain removers. Control variables would include the type and size of the stain, how long the stain remover sits, and what the stain is put on (like a t-shirt).

Ex. 3 - Alarm Clock. Control variables would include the loudness of the alarm, how long the snooze button is set for, and the time the alarm is set for.

Here is a link to an online quiz on variables. Give it a shot, one of the best ways to learn this is by lots of practice.

Introduction to Scientific Variables

This is a fun, descriptive video on scientific variables.

Scientific Method: Boat Day Part 1

Here is a video related to our activity in class. Come to class ready to change or modify your design from today. We will see who's design can hold the most washers without tipping or sinking. Remember the scientific method is all about problem solving and critical thinking.

Science over the Summer

Science in the summer? For many students science does not end in June, but continues throughout the summer. Whether it is investigating shells on the beach, conducting experiments at home, or engaging in a science camp, many kids continue to learn about the world around us even when not in school. Here are a couple of examples from our very own school. 

One of our former students, Samantha K. participated in Summer Ventures at ECU. Summer Ventures is a program that encourages learning and investigating science at a high level for juniors and seniors in high school. Samantha studied archaeology and neuroscience and even investigated Alzheimer's disease. 

One of our current students. Ruth H. also attended a science camp this summer. She went to a STEM camp which focuses on science, math, and technology. 

We also had many students complete at home experiments and projects. Here is a picture from Greyson T. Nothing like creating a homemade volcano with a rising pyroclastic flow. 

Post a comment about what you did this summer related to science. It could be anything from digging in the dirt to seeing how fast you could get your bike to go, to hanging out at Discovery Place. 

Science Interactives

There are many science interactives on the Internet. Try different ones and post a comment about it. Describe the simulation, write about what you learned, or what you liked about the simulation.

PHET Colorado

Weebly Science Interactives

Human Eye and Vision Problems

Here are several interactives that help with parts of the eye and correcting nearsightedness and farsightedness:

Parts of the Human Eye

Fixing Vision Problems

Here is a video that does a nice job describing vision problems.

Colored Filters and Objects

Here is the website we used in class to learn about how objects appear as the color that is being reflected.

Colored Filters

Refraction

Why does that diamond ring sparkle so much? Why does that fish in the pond not exactly appear where you thought it was? Why, refraction of course. Here are several websites and demonstrations that help with the concept of refraction.

Refraction

Refraction through a glass block

Winter Break

I hope everyone had a great winter break. What did everyone do? Send some pictures to me and I will post some pictures of what students did over break. Here are some of my pictures from a trip to Indianapolis last week. 

Indiana University football stadium

Downtown Indianapolis

More downtown Indianapolis

Downtown canal

 NCAA Hall of Champions Museum

Inside the NCAA Hall of Fame 

The Electromagnetic Spectrum

There are several websites that are helpful in describing the electromagnetic spectrum. Here are two of them.

http://www.darvill.clara.net/emag/

http://missionscience.nasa.gov/ems/index.html

In the above website there is also a video series that reviews each part of the electromagnetic spectrum. This video series can be found here: http://missionscience.nasa.gov/ems/emsVideo_01intro.html