As we have learned in science class, most of our transportation is powered by fossil fuels.  When fossil fuels are burned, harmful greenhouse gases and pollutants are placed in the air.  Fossil fuels are considered to be non-renewable sources of energy, because they come from the remains of living things more than 300 million years ago that can in no way be replenished at the rate at which we humans are using them!  Therefore, we designed experiments to determine how best to propel rockets using Alka-Seltzer + water as a model of an alternative and renewable source of energy.

Before designing our experiments, we made some observations of other chemical reactions to get a better sense of how to design our own experiments.

As with every controlled investigation, we only change one variable in order to observe the effect(s) of that one change. Think back: What was the ONE variable that your group decided to change to the Alka Seltzer + water chemical reaction?  What is another way to describe the ONE variable that a scientist changes in an experiment?  What is another way to describe what the scientist measures?

Each group only changed one variable in order to see the effect(s) of that one change.  Some groups changed the temperature of the water or the amount of water, while other groups changed the size of the Alka-Seltzer tablet.  The group above changed the temperature of the water, and predicted that the hotter water would dissolve the tablet faster.

As a scientific community, we shared our group's results. Through our first round of experimentation, we learned that increasing the temperature, increasing the amount/volume of water, and crushing the Alka-Seltzer tablet all decreased the amount of time it took for the Alka-Seltzer to dissolve (for the chemical reaction to occur).

Before designing our rockets, we took a break and visited the animals!  What was your favorite animal at the Environmental Study Center?

After experimenting to better understand how the size of Alka-Seltzer, temperature and volume/amount of water affect the speed of the chemical reaction, each group picked one variable (= independent variable) to change to their Alka-Seltzer powered rocket to get the rocket that can propel the highest.  Most groups changed the temperature or size of the Alka Seltzer.  Do you remember which group had the highest rocket propulsion?  Do you remember this group's independent variable?

Last but most certainly not least, we learned that there is no such thing as failure in science.  There is also no such thing as an "incorrect" hypothesis, because the whole point of testing a hypothesis is to learn something new (and learning something new is never wrong/right/correct/incorrect).  Instead, we say that our hypothesis was "not supported" and reflect on the process and possible limitations that occurred in the planning/design and execution of the experiment, and also evaluate and possibly re-think our original hypothesis!

Scientific Questions = Testable Questions

The scientific method (Dr. OPHERC) is a way to gather evidence in order to develop a scientific explanation of phenomena.  After making interesting observations (O), we identify problems (P) and questions for investigation.  However, it is important that the questions we ask are  "testable".  Without a testable question to start our investigation, we won't be able to gather meaningful evidence.

What is a testable question?

A testable question asks something that can be measured and observed (phenomena) through experimentation.  In other words, a testable question can only be answered by gathering evidence.  If your question does not require collecting data (qualitative and quantitative observations), then your question is NOT "testable".

Another way to think about is in terms of a controlled experiment.  A testable question asks how one change (independent variable) has an effect on something else (dependent variable).

Testable questions examine cause and effect relationships.  In other words, testable questions look into how an independent variable (IV) affects a dependent variable (DV).

Below are some example testable question formats:

• How does            (IV)           affect          (DV)         ?
• What is the effect of            (IV)            on            (DV)          ?
• What effect does            (IV)            have on            (DV)          ?

Testable questions are not related to personal preference, moral values, the supernatural, or things that cannot be measured.  Just remember: Testable questions do not ask about things that are NOT considered to be phenomena!

How do you turn a topic into a testable question?

Now it is time that we learn how to develop our own testable questions so that we can begin designing our own controlled experiments!  It is important that we choose topics that are meaningful and of interest to us. Therefore, the next question is, how do we take a topic (that interests us) and turn it into a testable question for investigation?

1.  First, make two lists.

• List everything you can measure about your topic of interest.
  
• List everything that you can change/treat differently to your topic of interest.
  

Example Topic: Tomato Plants

• List everything you can measure about the tomato plant (DV): height of plant, number of tomatoes, color of tomatoes, water content of tomatoes, number of leaves, mass of tomatoes, density of tomatoes, depth of the roots, circumference of tomato, pH of the tomatoes, etc.
  
• List everything that you can change/treat differently to your tomato plant (IV): amount of sunshine, type of light, amount of soil, type of soil, amount of compost, type of compost, species of tomato plant, amount of water, temperature, humidity, number of seeds in the pot, type of pot, pH of the soil, pH of the water, type of water, etc.
  

The first list are possible dependent variables.  The second list are possible independent variables.

2.  Next, pick one item from each list that interests you most.
You are essentially picking one dependent variable and one independent variable.

Example:

• Water content of tomatoes = Dependent Variable
  
• Amount of water = Independent Variable
  

3.  Finally, choose an appropriate testable question format and fill in the blanks with the appropriate variables.

• How does            (IV)           affect          (DV)         ?
• What is the effect of            (IV)            on            (DV)          ?
• What effect does             (IV)               have on           (DV)             ?

Example:
What is the effect of the amount of water given to a tomato plant on the water content of tomatoes?

Watch the video below on how to write testable scientific questions for investigation!  

In-Class Activity
Answer the questions below using information from the blog post and video.  Write the question and answer in complete sentences.

1.  What is a testable question? (highlight your definition in BLUE)
2.  What is NOT a testable question?
3.  What are the two parts of a controlled experiment that are in every testable question?
4.  What are the 3 steps to turning a topic into a testable question?
5.  Write 3 more testable questions about the tomato plant by following the steps in question #4.
6.  Follow the steps for turning the topic "Cafeteria Pizza at MS 88" into a testable question.  Make sure to outline each of the 3 steps to get full credit.