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By Leslie Hays



Basic Processes

We now have a textbook for students on the nature of science. It's intended to replace, or supplement, the inadequate first chapter of your text. It's designed to coordinate and help sequence several of the nature of science (NOS) lessons on the ENSI site. It is targeted to students in any science class, grades 7-10 (or beyond). It helps to satisfy virtually all the new NOS standards in NGSS and Common Core. If you've used any of ENSI's NOS lessons, you already know how powerful they are. This new book addresses most of the common misconceptions about NOS. It also provides information about the differences between good science, poor science, and pseudoscience. It offers clues for recognizing those differences, and opportunities to practice using those clues. "What's this magic book I've been waiting for all my life?" It's called Science Surprises: Exploring the Nature of Science. "Tell me more - like where can I see this book?" Say no more. It's available as an eBook, published with Smashwords. Click Here to get more information and a link to sample (and purchase) the new eBook Science Surprises.


 Another discrepant event problem is explored, to help students get familiar with the process of science. A plastic bottle with three holes covered with tape is filled with water and capped. Students predict what may happen as the tape is removed from each hole in turn, and hypothesize about the cause of the observed results.


Science often involves the forming and testing of hypotheses.


1. Scientific knowledge is uncertain, tentative, and subject to revision.
2. Hypotheses are testable possible explanations for natural phenomena (not just "educated guesses").
3. Predictions are the expected results of experiments, based on a given hypothesis.
4. Some hypotheses are better than others, in terms of...
--- how well it explains why something happens the way it does;
--- whether it suggests a discriminating test;
--- how simple it is, yet does the previous two things.


   Students will....

1. demonstrate their ability to form testable hypotheses, given a sample problem.

2. suggest valid and discriminating tests to challenge a hypothesis.

3. predict the reasonable alternative outcomes of those tests, depending on whether the hypothesis is correct or not correct.


 A 2 liter plastic soda bottle, with 3 small holes vertically placed on one side, about 6 cm apart, and covered with a vertical strip of duct tape or electrician's tape (about 18 cm long), so as to temporarily seal all three holes. The bottle is then filled with water, and tightly capped.



The holes can be made by heating a dissecting/teasing needle, small stirring rod (or cork-hole borer of about the same diameter), and "melting" each hole through the plastic.

Have a basin and towel close at hand during the demo.


 One 45' - 55' period.


 (see end of lesson for the formatted handouts).

 A one-page (two-sided) "Demo Report" sheet.


This lesson is very useful as an effective attention-getter which engages everyone in observing, hypothesizing, and testing hypotheses. This would be especially useful very early in the year as part of an introduction to the nature of science.

In any of the discussions expected with the class, select a few key items (important concepts) that lend themselves to interpretation, and introduce class to the Think-Pair-Share (TPS) routine dealing with those items. This is how "Active Learning" is done.

Have copies of the Demo Report papers ready for everyone, and have your 3-hole bottle ready to go.

If any of your students have had physical science or physics, they might already have a deeper understanding than the others, and perhaps should be asked to give others a chance to think about the underlying mechanism and respond before they offer their own ideas.

Discussion of Expectations and Explanations.




 1. The teacher stands on the demo table (to have the most impact), and shows the students the 3-hole bottle with water in it.

2. Teacher says: "I am going to uncover the first (top) hole in the bottle. I want you to show or write down on your Demo Report paper, in ink, and without any conversation, what you think will happen when I do this."
-----STUDENTS: Write their predictions quietly on their Demo Report.

3. Teacher asks for a sampling of some of the predictions, without judgment or question.
-----STUDENTS: may say: "Nothing will happen", or "Water will come out", or "Water will come out a little bit, then stop", or "Water will come out until it's below the hole", etc. If anyone says "Nothing will happen", ask that person to stand under the bottle while you uncover the first (top) hole (it's fun to get real dramatic about this!).

 4. Have the basin ready to catch some water. Have a student hold the bottle at top and bottom as the teacher carefully uncovers the top hole (do not squeeze the bottle, or you may influence the outcome).
-----STUDENTS: record what happens ("results"), and compares their predictions to what actually happened.

5. At this point, have your students try to figure out WHY this happened? Depending on your perceived sophistication of your class, you can either have them think and record their ideas on their paper, or possibly discuss it in small groups (2-5), and everyone records the group consensus.

6. Teacher steps down from demo table, and asks for a sampling of these possible explanations. You might want to then give (or ask for) the term for these ideas...these possible explanations: "hypotheses". Record these on the board or overhead projector.
-----STUDENTS: may suggest everything from "There's a magic spirit doing it", to "It's a trick bottle", to It's a vacuum, or suction", to "The hole isn't big enough", to "The air is holding it in", to "The air pressure is the same inside and out". Don't judge these yet. Sharing these just gives everyone the realization that there can be a variety of explanations. Later, you will review them with the class to see if they can see that some ideas may be "better" than others, and (most importantly) why.

7. Ask "how can we tell if one of those ideas (hypotheses) is correct?" We will "test" it. This means that we can plan a little experiment, and predict the likely outcome if the hypothesis is correct, and a different outcome if the hypothesis is not correct.

8. Teacher says: "One experiment we can do easily is to pull down the tape exposing the second hole, but before I do it, you must predict what you think will happen when I do that, if your favorite hypothesis is correct, and what will happen if you hypothesis is not correct. Think about this, and record your predictions on your paper."
-----STUDENTS: think and record their predictions.

9. Teacher asks for sampling of predictions (to share verbally with class).

 10. Teacher steps up on table again, and (with dramatic and suspenseful pause) pulls down the tape a bit more, exposing the second hole. Be sure basin is ready to catch water. "Now record your observations, and note if it matches your prediction."
-----STUDENTS: do this.

11. Teacher asks: "How many predicted correctly?" (note the number of hands). "Does this mean your hypothesis was correct?" (encourage "maybe" or "possibly", as opposed to "yes" or "no").


12. Teacher says: "If the results did NOT match your prediction, does this mean your hypothesis was wrong?" (encourage "probably" or "possibly", as opposed to "yes" or "no"). "Do you think it might be wise to consider a different hypothesis?" (hopefully, lots of "yes" responses).

13. Repeat steps 10-12 for the third hole. Hopefully, all or most of class will have predicted correctly this time, with a show of many hands. Ask "What does this tell you about how we can develop a realistic solution or answer to a problem in nature?"
-----STUDENTS: Hopefully, attempts to summarize what was done here will bring out the "observe - hypothesize - test - re-hypothesize - test - etc." sequence of the core process in science.

14. Now (or the next day) is a good time to explore the distinctions of "good" hypotheses from poor hypotheses. Go back to the initially proposed hypotheses. Ask for "gut-level" opinions of which one or two are "best", and which one or two are poorest. Mark those accordingly. Now ask if anyone can explain WHY they selected those items. Hopefully, out of this dialogue, you can bring them to realize at least three components of a "good" hypothesis:
----- a. it would explain the problem
----- b. it's testable, by one or more discriminating tests
----- c. it's as simple as can be, and still fulfill the first 2 items.

15. Under "testability", the question of whether supernatural explanations are testable my arise. This aspect is covered in our lesson "Sunsets, Souls, and Senses". This would be a good time to go on to that lesson.

16. For homework (started in class, if time), have the students apply their understanding of the use of a hypothesis to a slightly different problem: the same bottle used before, but held on its side, with the three holes facing down. (see the Demo Report form), and finish the additional questions on the form. CAUTION students to melt/or drill the holes only under adult supervision.

17. Subsequent discussion should help to reinforce the basic concepts, and clarify where necessary.


The series of items below can be presented as an open-ended test, or with carefully selected and fashioned multiple choice items, designed to reveal if students can critically select the MOST reasonable answers, based on their accurate understanding of this process.

1. Show or present on paper another discrepant event ("problem"). Ask students to suggest (on paper) one or more reasonable hypotheses.
2. Ask students to describe a test that would discriminate the validity of that hypothesis from the others.
3. Ask students to state specific predicted outcomes of the test...IF the hypothesis is TRUE, and IF the hypothesis is NOT true.

4. If there was discussion of distinguishing between "good" (reasonable) hypotheses and poor quality hypotheses, their assessment should include a question or two in which they are expected to select, from a list of candidate hypotheses, the one (or two) which would probably be "best" (explains, testable, simplest).



1. Do another discrepant event lesson (e.g. The Great Volume Exchanger).
2. Do the Sunsets, Souls, and Senses lesson.
3. Do the Mystery Boxes and/or the Find the Washer lessons.
4. Do the Perception is Not Always Reality lesson on illusions.

5. This lesson could be done in a shorter, somewhat simpler fashion, focusing on the predictions and the experimental outcomes. However, if it is done this way, be sure to get students to reflect afterwards on what was probably going on in their heads from one prediction-result to the next prediction-result, namely, they were trying to figure out what was going on to cause the observed results...in other words, they were hypothesizing, and (hopefully) were basing their new predictions on revised hypotheses (as opposed to simply guessing, which some may do, also). You should also get them to realize the distinction between a hypothesis and a prediction (see Associated Concepts), and also discuss what makes a good hypothesis.


 See sources and suggestions for discrepant events in The Great Volume Exchanger lesson.


Some of the ideas in this lesson may have been adapted from earlier, unacknowledged sources without our knowledge. If the reader believes this to be the case, please let us know, and appropriate corrections will be made. Thanks.

 1. Original Source: Leslie Hays

2. Modified by: Gary Niva, Jerry Quissell, Karin Westerling, & Lucille Williams.

3. ENSI / SENSI original developed by:

4. Reviewed / Edited by: Martin Nickels, Craig Nelson, Jean Beard 12/15/97

5. Edited / Revised for website by L. Flammer 8/98

 The following is a useful worksheet for students to complete during the demo. A pdf version follows this (for easier printout which is copy-ready).

 Name_________________________________ Per.____

The Three Hole Bottle Demo Report

 1. Compare the bottle used with the diagram at right. Point out any differences noted, or sketch the demo bottle as you see it.  

 2. PREDICT what you think will happen when your teacher pulls the tape off the top hole. You can describe the expected result, or show it on the diagram at right.  

3. Show (and/or describe) what actually DID happen.  

4. How would you explain what happened? (In other words, what do you think caused to happen what did happen?). You might be able to list 2 or 3 reasonable, possible explanations.  



5. Select one of your explanations (your "most likely" one, mark that one with an X), and based on that possible explanation, what do you predict will happen when the tape is pulled down exposing the second hole? (Describe, and/or show on the diagram).  

6. Show (and/or describe) what actually DID happen.  

7. Did the results match your prediction?

----- If so, what does that suggest about your possible explanation (hypothesis)?

----- If not, what does THAT suggest about your hypothesis?

8. If necessary, propose a second hypothesis:


9. Now, based on your best hypothesis, what do you predict will happen when the tape is fully removed from all three holes?  

10. Show (and/or describe) what actually DID happen.  

11. Did the results match your prediction?

----- If so, what does that suggest about your possible explanation (hypothesis)?

----- If not, what does THAT suggest about your hypothesis?

12. Summarize briefly what this entire experience tells you about how science solves problems.



13. Explain why some hypotheses are better than others; in other words, what are the characteristics of good hypotheses which may be lacking from poor hypotheses?


14. Now we'll go back to the bottle, with the tape covering the three holes and the bottle full of water, but the bottle will be held horizontally, with all the holes facing down.

15. Assuming your best hypothesis for the actions with the vertical bottle might apply as well to the horizontal bottle, predict what is likely to happen when the tape is removed from the first hole (show and/or describe):

16. Predict what is likely to happen now when the tape is peeled down further to reveal the second hole (show and/or describe):

17. Finally, predict what is likely to happen when the tape is removed from all three holes (show and/or describe):

18. If possible, test your hypothesis by using the teacher's bottle, or building your own bottle and performing the above actions. Record all observations. Write up your work using our lab report format. Your peers will critique your work in our "Three-Hole Bottle Symposium".


19. Explain how the modern flush toilet (that miracle of human technology) is similar to the bottle systems used in this activity. Do this neatly, using diagrams as appropriate.


 The following two pages are in Adobe Acrobat pdf format in order to maintain their intended layout for handouts. Only the first page is showing. To access both pages (for enlarging and copying, etc.), you will need to download the free Acrobat Reader from Adobe (unless it's already installed in your system). Then just click on the blue file name at the bottom of the first page. You will see the "Acrobat Exchange" application loading, then the pages will display. You might need to shift-click and drag the lower left corner of the page to enlarge it.




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