Lesson 10

Conducting a Controlled Experiment: Jason's Revenge - or is it?

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Objective

SWBAT collaboratively conduct a controlled experiment, collect data as evidence, and write a four part conclusion to communicate their findings.

Big Idea

How do scientists analyze data in a controlled experiment, and communicate their findings? Students conduct their controlled experiment, analyze their data to write a four part conclusion, and have a little fun with a science induced soda-pop geyser.

Investigation Set Up

This is Day Two of a Two Day Lesson.  Click here for Day One of this investigation: Planning a Controlled Experiment:  Jason's Revenge - Or Is It?

On Day One of this investigation, students worked collaboratively to plan a controlled experiment to investigate if candy dissolves faster in water or lemon lime soda.  

On this second day, students will conduct the experiment, collect data, and write a formal conclusion.

Connection to the Next Generation Science Standards

In this investigation, students demonstrate understanding of the following Science Practices; conduct an investigation collaboratively to produce data to serve as the basis for evidence, using fair tests in which variables are controlled and the number of trials considered (5-PS1-4); measure quantities such as weight to address scientific problems (5-PS1-3); and demonstrate the Crosscutting Concepts of using a cause and effect relationship to explain change (5-PS1-4); and that standard units are used to measure and describe physical quantities such as weight, time, temperature, and volume (5-PS1-2), (5-PS1-3).

*  Although students are beginning to address the Disciplinary Core Idea that matter of any type can be subdivided into particles that are too small to see, but even then the matter still exists and can be detected by other means (5-PS1.A) - that is not the emphasis for this lesson and will be fully explored in later lessons in the unit.  This lesson will however, become another "touchstone" lesson for this concept

 The Preparation Time for This Investigation is approximately 15 minutes. 

Materials Needed

1 balance and mass cubes for each team

2 plastic cups to fit into each balance 

1 graduated cylinder for each team

2 Hand lenses for each team

1 timer for each team

2 Mentos Candies per team (and 1 additional pkg. of 13 for the demonstration)

1 liter of Diet 7 Up at room temperature (unopened)

1 liter of Diet Coke at room temperature (unopened)

1 test tube (for demonstration)

1 index card

1 materials tub per team

 Preparation I did the following to prepare for this investigation:

  • Assemble a materials tub for each team that includes all needed materials.
  • Set a table outside in the grass, away from the building for the pop geyser.

Focus & Motivation

5 minutes

It doesn't take much to get this group focused and motivated - they are ready to go!

Share Lesson Objective & Success Criteria

Note:  Consistent with the Sheltered Instruction Observation Protocol, I am now including a language objective with each lesson.  These objectives were derived from the Washington State ELP Standards Frameworks that are correlated with the CCSS and the NGSS.

I share the lesson objectives and success criteria:

Learning Objective:  I can collaboratively conduct a controlled experiment, collect data as evidence, and write a four part conclusion to communicate my findings.

Language Objective:  I can communicate a sequence of events in writing using temporal and other transitional/linking words (e.g. first, next, therefore, etc.).  [ELP.4-5.9]

Success Criteria:  I have completed all steps of the process correctly in my Science Notebook.

Team Investigation

55 minutes

I call the team leaders back to collect their tub of materials.  

Calculate the Mass of the Mentos

Once all teams have their supplies, I tell my students that before we begin, I would like them to use their balance to calculate the mass of each Mentos candy, one of which is Jason's and the other is Seth's.  I ask students, "Why are we doing this?  At first students respond that we need to be "fair."  I pounce on that and say, "Yes, this needs to be a "fair test.  How do we make this a "fair test?"  I am hoping to get the response that we are controlling our variables, but it takes a bit of questioning to get there.

Not only do I want students to control their variables, but I also want them to have practice with measurement.  I will take every available opportunity to have them practice this important skills.

Review Procedure & Safety Rules

Once students have assured themselves that the two Mentos candies have the same weight (mass), we review the procedure together.  My students are excited about this first experiment, and I know if I don't take a few minutes to do this step - they will rush into this investigation and miss important understandings.

Before I give the "go ahead" signal, I ask that teams make decisions about who will do what job, so that there is no arguing during the experiment.  I remind them that my rule is that if your team argues during an experiment, then you could lose the opportunity to do the experiment.  We also quickly review safety rules.

Experiment

This is the exciting part!  I give the go ahead for students to begin their experiment, as soon as all teams have assigned their jobs.  Teams are now becoming very efficient at deciding who does what.  They know that because hands-on Science is a frequent activity, they will always get a chance to participate.  They are learning great collaborative skills.  Some students take on the job of labeling the cups, others have the job of measuring the soda, or measuring the water, while others take care of timing the intervals.  Everyone participates, everyone cooperates, and everyone is engaged.  As they are working, I am moving in between groups, clipboard in hand.  I make anecdotal notes and observations of student talk, any student difficulties or misconceptions.

Analyze Data & Make A Claim

Once students have finished collecting their data, I ask, "What is our next step?"  By now students know to look at Plaid Pete's Guide to Planning A Controlled Experiment to help them find their way.  They are also now familiar with the process of making a claim that is supported by evidence.  I instruct them to go to their Science Notebooks, and turn to where we left off.  Directly after the Data section, they write the following:

Claim & Evidence

Rather than having them write it twice, I just have them draw a line directly below the & symbol to construct a T table.  Students then work in their teams to list their claim and the evidence they collected that supports their claim.

When all students have finished this section I say, "When scientists finish a controlled experiment, they share their information in a special section called a Conclusion.  A scientific Conclusion has 4 basic parts that are most always included in some way.  Now you are ready to learn how to write a 4 part Conclusion."


Instruction

15 minutes

I ask my students, "What do we need to begin this section?"  They know by now that we need a heading.  I write:

Conclusion

1.  I tell my students that the first sentence of a conclusion includes a statement that gives the hypothesis and begins like this:

I predicted ________.

I have them turn back in their Science Notebooks to find their hypothesis and copy it after the sentence stem I have given them.

2.  I tell them that the second part of a Conclusion summarizes the data that was collected.  We discuss what the word "summarizes" means and agree that it tells just the main parts, not the whole thing, and that it just gives the facts.  I explain that when they are using quantitative or numerical data to prove their claim, they will include the high and low data, and when they are using qualitative data, two observations in time will be included.  I ask, "What kind of data did you collect that will help you prove your claim?"  I have them turn and talk to their team members.  This is an important step, as some students will be confused in this particular experiment and will focus only on the time, without linking it to their observations.  Students share out and I give them a sentence stem to begin the next part in their Science Notebooks (to be used with the data they collected in their team):

I observed that after ___ minutes, the candy in Cup A _____, while the candy in Cup B ________.  After ___ minutes the candy in Cup A _____, and the candy in Cup B ___.

3.  I tell them the third part of a Conclusion analyzes the data that was collected.  We discuss what the word "analyzes" means, and agree that it means "explains what the data means."  I give them the sentence stem to begin their next sentence:

The means that ________.

4.  Last, I tell my students that the final part of their 4 part Conclusion must state whether their prediction was correct, or incorrect, and begins with a special word.  I give them their last sentence stem:

Therefore, my prediction was (correct/incorrect - choose one). (At this point I allow students to use the words hypothesis and prediction interchangeably, however; I do tell them they are not exactly the same thing)

I add the following to my chart, and direct the students to add them to their foldables under the last tab.

6.  Conclude Your Investigation/Communicate Findings

  • State hypothesis (I predicted . . .)
  • Summarize data (I observed/recorded . . .)
  • Analyze Data (This means that . . .)
  • State if prediction is correct/incorrect (Therefore . . .)

I tell my students that now and forever, whenever they conduct a controlled experiment, they will be expected to write a 4 part Conclusion!  This is a completed student conclusion.

Reflection & Closure

15 minutes

Class Discussion

Once teams have finished their conclusion, I ask teams to think back for a minute and decide, based on the evidence - who was right?  Was Jason right?  Did Seth cheat when he gave Jason lemon-lime soda to drink, while he drank water?

Note for Teachers

I don't know what you will find, but I did this experiment 5 times, because I didn't believe my results.  Like many of my students, I thought the Mentos in the pop would dissolve faster - but it doesn't.  The reaction between the Mentos and the pop is a physical reaction, and not a chemical reaction.  The reason behind the "Mentos Explosion"  has been debated by scientists since the original video went viral on You Tube.  A good explanation is given by The American Journal of Physics.

What I am really hoping is that some really bright student will pop up and say, "But we don't have any evidence he did it on purpose - so it doesn't matter what the experiment showed!"  Then - I will know I have somebody who is thinking!

Class Demonstration

After we have had an opportunity to discuss this for a few minutes, I tell my scientists that I have a little demonstration to show them.  I take them outside to the lawn area where I have set up materials to create a Diet Coke/Mentos geyser.  I explain that this is a reaction that has puzzled some of the best scientists a few years now and created quite an argument about why this happens.

I follow the steps outlined in the video below.  Boy, do I get some wonderful questions - that of course I do not answer!  I have now started a "Science Questions" chart in the classroom that we will be adding to, and I will attempt to address them as we move along in our unit.  Here is a video clip of our Mentos geyser  I think the student videographer was more interested in the geyser than the faces of the students - so sorry!  You won't get any of those in this video.

I remind my students to take home their Science Notebooks tonight to study for tomorrow's Mid-Unit Assessment - as anything they have written in there is fair game!

Note:  Do have the discussion with your students about not trying this without adult supervision and not putting a bunch of Mentos in their mouth and chugging Diet Coke.