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!

Limitations are parts of an experiment that keep the scientist from producing fair and reliable data. Even a very well planned out experimental procedure can lead to "mistakes" and produce less than perfect data.  As scientists, it is important that upon completing an experiment, that we reflect on all possible limitations that may have influenced our data.  These limitations should be included in the scientist's conclusion.

Below are the four categories of possible limitations in science that can keep the scientist from producing "perfect" data:

1. Independent Variable: Every experiment should only have one independent variable.  If there is more than one independent variable (part changed by the scientist), then it will be impossible to determine what effects were caused by a particular change.
2. Multiple Trials: Repeating a science experiment is an important step to verify that your results are fair and not just an accident.  For a typical controlled experiment, you should have at least 3 repeated trials (more is better).
3. Human Error: Experimental error is always possible as human beings.  Any time we make a qualitative or quantitative observation, there is a degree of uncertainty.   This may be due to pre-existing limitations in the measuring equipment (ex: broken thermometer), or of the measuring techniques, or perhaps the experience and skill of the experimenter.
4. Constants: Every experiment should have as many constants as possible.  Constants are parts of the experiment that a scientist keeps the same to insure that the only part of the experiment affecting the results is the independent variable (the part changed by the scientist).

Assignment:
Identify one type of limitation in each experiment (questions 1-3) that you think will most affect the reliability of the data. Make sure to explain why you chose the particular limitation.  YOU DO NOT NEED TO WRITE THE QUESTIONS.

1.  Ashik filled 3 pots with EcoScraps soil and labeled them A, B, and C.  He then placed 1 radish seed in the middle of each pot.  Ted added 1 teaspoon of fertilizer to pot A, put 2 teaspoons in pot B, and no fertilizer in pot C.  After using a different amount of fertilizer in each pot, he placed pot A on a sunny windowsill, pot B on a shady windowsill, and pot C in a dark closet.  Ashik watered each plant with a ½ a cup of water every day. As he measured each plant throughout the month, Ashik wrote the height of the plant (in centimeters) in his data table for trial one.  Ashik repeated the same experiment for trial 2 and trial 3.  Identify one limitation in Ashik's experiment.

2.  Paula wanted to find out if the type of soda (diet coke vs. regular coke) affected the time it takes to "go flat" (lose carbonation). She figured the best way to determine when the soda went flat was by tasting the sodas every 30 minutes.  For each trial, Paula set a timer for 30 minutes, then tasted the diet coke first, immediately followed by the regular coke.  She recorded whether or not the soda was flat after each taste test.  She performed a total of 5 trials.  Identify one limitation in Paula's experiment.

3.  Rashonne wanted to find out what color Crayola marker (red, yellow, green, orange, blue, purple) dries out the fastest.  She purchased one box of markers and set out all 6 colors on a flat surface in the same location with the same temperature, where each marker received an equal amount of sunlight. She removed the caps and checked them twice a day to record the time for each marker to dry.  Identify one limitation in Rashonne's experiment.

4.  True or False: "If a procedure is very well planned out, then there will be no mistakes in the data."  Explain your choice.

An experimental procedure is a detailed, step-by-step "recipe" for conducting a scientific investigation. A strong experimental procedure is so detailed and complete that any other scientist can replicate the experiment and results.  

Each time an experiment is repeated is called a trial.  In order to gather reliable, fair data from experimentation, we must always perform multiple trials (at least 3) for every experiment.  

If you have struggled to write a strong experimental procedure, you are not alone.  Writing a procedure for making a peanut butter and jelly sandwich or drawing a simple smiley face can even be tricky! 

Check out Ms. Shon's "Pocket Guide for Writing a Procedure" to help you edit your procedure to make sure that any other scientist is able to replicate your experiment and results. 

Ms. Shon's Pocket Guide for Writing a Procedure
When writing a procedure, you should....

• Number steps
• Start each step with a verb (action word - list of examples follow)
• Include only ONE action in each step
• Include measurements (size, how much, how far, how many, etc.)
• Use pictures and labels for hard to explain parts
• Use the present tense (fill, place, measure, pour, etc.)
• Avoid transitional words or phrases (next, finally, in addition to, therefore, however, etc.)

Variety of Verbs
Pull from the list of verbs below to improve your experimental procedure!

• Gather
• Label
• Measure
• Observe
• Count
• Determine
• Calculate
• Average
• Clean
• Record
• Throw out
• Cut
• Lift
• Listen
• Repeat

Homework: 
Due Tuesday, December 17, 2013.
1.  Copy Ms. Shon's pocket guide for writing a procedure in your science notebook.
2.  Edit your experimental procedure using the guide (SNVP) above.  Write them in your science notebook. 

Controlled Investigation
As we have already learned, a controlled experiment involves changing one thing to observe and measure the effects of that one change.  In a controlled experiment, the scientist has total control over the environmental conditions.  The temperature, humidity, amount of light, amount of noise, materials, etc. can all be controlled and monitored by the scientist throughout the investigation.  For this reason, controlled investigations are usually done indoors, such as in a classroom or kitchen.  

Example Controlled Investigation Questions: 

• How does the pH of water affect the growth (height) of a fig plant?
  
• What is the effect of the amount of stuffing in an Oreo on the grams of fat in one Oreo?

Field Investigation
A field investigation involves observing and measuring plants and animals (including people) in their natural habitat or environment without changing, harming, or altering the setting or any part of the test subjects.  Like in a controlled experiment, the scientist chooses to observe and measure how one change (IV) has a measurable effect (DV) on something else.  The key difference is that the scientist does not change anything in the environment, but rather, gathers data on the conditions or situations that already exist.

Example Field Investigation Questions: 

• How does the time of day affect the number of fish a penguin eats?
• What is the effect of the temperature in Prospect Park on the number of ducks in Prospect Park Lake?

Design Investigation
A design investigation involves changing the design of something (IV) in order to create the effect desired by the scientist.  For example, the scientist may wish to design a paper rocket that will travel the furthest distance.  Therefore, the scientist might test his/her rocket with 3 different fin lengths. Once he/she has the results of the experiment, the scientist can then create the final product and test it via a controlled experiment to see if it has met the goal.

Example Design Investigation Questions:

• How does the length of the fin on a paper rocket affect the distance the rocket travels?
• What is the effect of the circumference of the wheel on the speed of the wooden car?

Secondary Research Investigation
A secondary research investigation involves using data (evidence) that has already been gathered by other scientists to answer a question.  Therefore, there is no direct "experimenting" done by the scientist in a secondary research investigation.  The data that is used can come from the internet, in print, or other sources.  The major advantage of secondary research investigations is that the scientist can take advantage of very large data sets that have been gathered over many years or over very large areas.  Questions that involve studying long term cause-and-effect relationships (ecosystems, climate, water quality, etc.) may be best suited for this type of investigation.  

Example Secondary Research Investigation Questions:

• How does the increase in social media (Facebook, Twitter) use around the world affect the amount of time people spend with their families?
  
• What is the effect of the increase in carbon dioxide in the Earth's atmosphere on the rate of glaciers melting in the Arctic?

Assignment
Complete the questions below in your science notebook.  Write the questions for #1-7.  You do not need to write the questions for #8-12 (just restate and answer in complete sentences for 8-12).

1.  What are the four types of scientific investigations?
2.  Why are controlled investigations/experiments usually conducted indoors?
3.  How is a field investigation like a controlled investigation?
4.  How is a field investigation different from controlled investigation?
5.  What is a design investigation?
6.  Can a secondary research investigation use data from different sources?  Explain.
7.  What is the major advantage to a secondary research investigation?
8.  Jason wants to find out if the members on his soccer team who wear cleats during a game kick the ball further than those who do not wear cleats.  What type of investigation will Jason conduct?  Explain.
9.  Brandon wants to find out what type of video game console heats up to a higher temperature.  Brandon will use the exact same game in each console and will play for the exact same amount of time in the same room.  What type of investigation will Brandon conduct?  Explain.
10.  Jennifer wants to know if the amount of sleep people receive over a lifetime has an effect on how long they live.  What type of investigation will Jennifer conduct?  Explain.
11.  Alec wants to find out how the circumference of his skateboard wheels affects his speed.  Alec tests out three different wheel sizes.  What type of investigation will Alec conduct?  Explain.
12.  Ms. Shon wants to know if the amount of rainfall has an effect on the number of roses that grow on her rose bush.  What type of investigation will Ms. Shon conduct?  Explain.

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.  

What is a controlled experiment?

A controlled experiment is an experiment that is conducted under a setting that is “controlled” by the scientist with the least possible influence from outside factors.  A controlled experiment compares an experimental group with a control group in the exact same conditions with the one exception of a special/different treatment given to the experimental group. 

The control group represents the "normal", "standard" or untreated condition.  The experimental group is the one part of the experiment that is changed/manipulated (given different treatment).  The constants are everything else you keep the same to ensure a fair test.

Francesco Redi's Controlled Experiment: Do maggots (young flies) come from rotting meat?

To better understand controlled experiments, let's look at Francesco Redi's famous controlled experiment on maggots and meat as an example.  Francesco wanted to find the answer to the question, "Do maggots (flies) come from rotting meat?".  This may seem like a really silly question, but in Francesco Redi's day (1600s), people actually believed that flies and maggots were generated spontaneously from meat.   Take a look at Redi's experiment below.

Homework

Watch the video below on a controlled experiment studying the effect of ozone on plants  Then answer the questions in your science notebook in complete sentences.

1.  What was the question the scientists were trying to answer through this controlled experiment?
2.  How were all of the plants treated the same?
3.  What is a variable?
4.  What is the variable (one thing changed) in this experiment?
5.  What was the control/control group in this experiment?
6.  What is a control/control group?
7.  What do the scientists measure/record everyday in this experiment?
8.  Why do you think it is important that scientists only test one variable in an experiment?

Extra Credit:

Watch the video of how students set up a controlled experiment to investigate the effect of mirrors on dolphin behavior: http://vitalny.pbslearningmedia.org/resource/737ed8f2-10bb-484e-9b75-e3f19a91f3a4/dolphin-dive-05-test/
Then answer the questions below.

1.  What was the control test/group in the dolphin experiment?
2.  What was the experimental group in the dolphin experiment?
3.  How do you think the students could have improved their experiment?