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Adapted by
Steve Randak, Tom Watts, and
Michael Kimmel


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 ). Click Here to get more information and a link to sample (and purchase) the new eBook Science Surprises.


 Use of a discrepant event piques curiosity and provides an excellent metaphor for a problem in science that can be addressed in a scientific way. Water is poured into a "magic" box, and out comes a much larger volume of water (or other liquid).


 Science is uncertain because scientists can make more than one workable model to explain their observations.


1. Models / Scientific Authority are challenged, confirmed or modified according to experimental results.

2. Uses observation, prediction, hypothesis-/model-building, collaborative learning.


   Students will....

 1. work in collaborative groups to design a paper model (diagram) of the inner workings of the "volume exchanger".

2. be able to explain their models of the "volume exchanger" to the class, and defend its design.


 1 gallon plastic jug with about a meter of rubber or plastic tubing inserted through a hole about 2/3 above the bottom of the jug, sealed with silicone seal around the hole, and filled with water to just below that hole; large funnel, 1-liter beaker with some water, 3-liter beaker for catching water, two large boxes. A one liter plastic soda bottle would also work, but it might tip over, and it also doesn't hold as much water as a gallon jug.


 1 45-55 min. class period, with periodic follow-up, classroom discussions, possible student demos of their working models (as a student challenge).


 none (they can use their own notebook paper)





Before using any of our Nature of Science lessons, be sure to read our General Background Information, with our Rationale and our Approach, and tips for Presenting the lessons for maximum effect and Dispelling some of the popular myths about science.

1. This lesson is an excellent one to use before or after the "Mystery Boxes" or "Find the Washer" lessons, since they provide additional experience in thinking in a scientific way.

2. See the attached drawing (end of this lesson) for construction of the Volume Exchanger. First prepare a large box with an appropriate, neatly printed sign on its side (use computer, if possible), printed with something like: "Magic Matter Maker" ®.

Before class, and out of sight of students, fill the exchanger jug with about 2-3 liters of water (up to just below the tube exit; see diagram) and place it in the main box (with the sign on its side), which is on top of another box or other support, to allow for the collecting of water in large glass container (e.g.3 liter beaker) on the desk. Place a large diameter funnel, with a long stem or rubber tube extension, through the top of the box and into the gallon jug. [This set-up will work by the principle of a siphon, but never tell this to your students]. Finally, have the smaller beaker handy with about 150-200 ml water in it.

It's most impressive to set it all up on a tall cart in a prep room, if possible, then wheel it out into the classroom with great fanfare. You can prepare as many gallon jug "Exchangers" as you might need ahead of a series of classes, then all you need to do is to remove the "used" jug-and-tubing and put a fully charged jug-and-tubing into the same box between classes, out of sight of student eyes, of course. A pan and some toweling can be placed in the bottom of the box to catch any little spills or dribbles, and keep the cardboard box from getting soggy from repeated use.

Also, be sure every student knows to what 3-4 person team he/she belongs.




 INTRODUCTION: Make a grand announcement to your class, something like the following:

The "Magic Matter Maker" ® is truly the wonder of our time! I've invented a fantastic new machine which, under ideal conditions, will spontaneously generate twofold, nay tenfold, the amount of liquid matter placed into the "Magic Matter Maker" ®. I'll be rich!...famous!!....I'll retire to Tahiti!!!

Cloaked in modern technology, the "Magic Matter Maker" ® is constructed of polysaccharide resin-core walls, super-hard ferrous fasteners, with high tech petroleum derivative access and distribution devices. This unique, amazing system uses a small amount of water as a "seed" to produce much larger amounts of liquid matter.

After a brief rejuvenation period, this truly marvelous "Magic Matter Maker" ® is again ready to do its job. During the rejuvenation period (usually 24 hours), the "Magic Matter Maker" ® must remain totally undisturbed. The "rest" period allows the molecular multiplication forces to be reconstituted within the "Magic Matter Maker" ®. It has been found that human presence seems to seriously hinder or block the free flow of this force back into the "Magic Matter Maker" ®, thus delaying its rejuvenation.

Imagine the potential! A "Magic Matter Maker" ® the size of an ordinary railroad car could supply the water needs of an entire community at a fraction of the cost of our current normal system.

We are still in "beta testing" of this device, so it isn't available commercially just yet. In fact, there are still a few bugs to work out. However, it seems to work well enough that I can show it to you as an example of a natural phenomenon, so you can practice using your powers of observation, and also practice trying to figure out how it works, much as a scientist would.

1. Ask everyone to observe very carefully. You may want to have everyone set up a formal sheet of notebook paper, with name, etc., and begin by sketching the set up as they see it. You may also want to appoint a student volunteer to be an "assistant"

STUDENTS: Lay out a sheet of notebook paper, and sketch the set up; a student volunteer comes up to read volume of water in small beaker, and announces this to class.

2. Ask everyone to observe everything that is done, in careful detail. Then pour water into the funnel (about 100 ml from the smaller beaker) until water starts flowing out of the side tube and into the large beaker. Stop pouring; Ask the volunteer to read the volume in the small beaker NOW. Calculate the difference, and announce to class the amount of water actually poured in (or, better yet, ask them to do this).

STUDENTS: record their observations, including the amount actually poured in.

3. Describe enthusiastically (or ask) "what's happening?"

STUDENTS (or you) say: "more water is coming out than went in", or something to that effect.

4. When the water stops flowing, ask the volunteer to read the final volume in the large beaker.

STUDENT: volunteer reads volume, announces it to class (which they then record).

5. Tell students to finish their written description of what happened. Use observations, be specific.

6. Announce: "You have all experienced something, a phenomenon." Ask "What's the problem here?"

STUDENTS: sooner or later should indicate that the main problem here is something like "how does it work?". Have them add below their diagram and observations the word "Problem", and state the problem briefly in their own words.

7. Have the students get into their pre-assigned teams of 3-4. Ask every team to develop a group model (hypothesis) of how they think the Volume Exchanger works. Each team should put its final consensus diagram on butcher paper, or on overhead transparencies. They should also write down HOW their version works.

STUDENTS: get into groups, discuss their ideas, then prepare their drawings and explanations.

8. Have teams post their drawings (or take turns coming up to the overhead), and when all are posted, have spokesperson from each group describe the workings of their Volume Exchanger. Students may have to defend their model orally if there are challenging questions from class and/or teacher (encourage this).

STUDENTS: take turns showing and explaining their diagrams and answering questions about them.

9. Have students discuss which model seems most likely to be the best one, and why they think so. [If possible, bring up Occam's Razor: "simplest is best, if it works"]. Is there a class consensus? At some point, you might want to ask the students if they recognize what their "possible solutions" would be called, technically; if none offer the word "hypotheses", then introduce that label.

STUDENTS: participate in discussion. May or may not be consensus.

10. Ask students how they might "test" one of the models, what they might do (short of peeking inside) that would give them a clue as to whether that model matched the teacher's setup, or not.

STUDENTS: present various ideas for testing. You could jot them down on the overhead or chalk board.

11. Ask the class to select one test of the Volume Exchanger that you can perform (e.g. using colored water, etc.). They can then evaluate their own models further, based on the new data. [Do this only if you have a second generator all ready to go; remember the "rejuvenation period" needed. If not, tell your class that you will do the test tomorrow].

STUDENTS: (by vote or other means) select the one test for you to do. If you can comply, do the test. If not, promise to do it tomorrow.

12. Do NOT reveal the inner workings of the Volume Exchanger. They should never know for certain, since scientific models are approximations of nature, we can't ever know for sure if our models are accurate. EXTRA CREDIT CHALLENGE: Invite students to construct their own home-grown models based on their group or individually hypothesized model, and bring into class for demonstrations.

STUDENTS: (some) may choose to construct their own exchangers and bring them to class to demonstrate.




1. Observe: are students engaged? Are they coming up with hypotheses (making sketches and writing explanations which attempt to show how it works)?

2. Collect their papers; perhaps one from each team, selected by the team members by vote. Check to see that each student (or team)

 - observed (sketched the set up, recorded how much water went in, and how much liquid came out, plus any changes in the liquid).

- recognized a problem (and stated it)

- proposed a hypothesis (with diagram and verbal explanation)

- suggested a test to challenge the hypothesis.

3. Each group will select the model it prefers and defend this model.

4. They may also critique other models in oral form.

5. QUESTIONS: to be answered individually for homework or as group assignment:

 a. Is it possible to know the working of the inside of a device without seeing the inside? Explain your answer.

b. Why do you think that students can see the same event such as the Volume Exchanger, and have different explanations of how it functions? Explain your answer.

c. Should scientific authority be challenged and questioned? Explain your answer in terms of this activity.






PROMOTE SKEPTICISM: Whenever you present something seemingly magical or "supernatural", train your students to shout out "TRICKERY" all together. For example, after you show them the Magic Hooey Stick, with as much flair and aura of mysticism as you can muster, if nobody raises any doubts or challenges its magic, ask them "Is there anyone who suspects that this might not be magic, but rather has some natural or physical explanation? Does anyone suspect 'trickery'?" When you get some agreement, tell them "Well, I should hope so! Good scientists are always skeptics. Whenever you see something (at least in this class) that is presented as mystical or supernatural, I want you all together to shout out 'TRICKERY!' Got it? Good. Let's do it: 1,2,3, TRICKERY! Very good. Don't forget, now. Then, we'll explore the phenomenon further." It's good to reinforce this with one or two additional examples of "magic", or discrepant events, so they can practice shouting "TRICKERY!"

If they ask what a skeptic or skepticism is, explain that skeptics try to hold an open, provisional approach to the explanations for unusual phenomena. They realize that the world holds many natural illusions. They challenge mystical or supernatural explanations with close observation and reasoned logic, because 1) such "explanations" do not really provide any details, and 2) such explanations, upon closer scrutiny, usually turn out to be false, and are replaced with ones that fit known natural laws. Good scientists always assume natural explanations are working, and test them by trying to disprove them. If they survive the challenge, they are stronger for it. Remember the dictum: "Extraordinary claims require extraordinary evidence."

There are, of course, many kinds of "discrepant events", or seemingly magical phenomena, which you can use in place of (or in addition to) The Great Volume-Exchanger. The challenge comes in finding a fairly simple, easy to repeat "event" which is biological in nature (for biology or life science classes). If you have one, or develop one, be sure to send it to us to share with others. CONTEST: The best BIOLOGICAL discrepant event ideas will win a prize (winners and prizes to be selected by the ENSI faculty).

Here's one biological one I'll share: Our Blind Spot. This makes an interesting opener on first or second day of school. Tell your class this will be to see if they can follow directions! "I want to show you that our eyes are not perfect. Take a piece of paper and put a spot in the center. Then, about 5 cm to the left (or 3-finger-widths), make a capital L, and 5 cm to the right, make a capital R. Now, put your hand over your left eye, and stare at the spot with your right eye as you move your head closer to the paper (to around 20 cm distant). You should notice that something disappears. What is missing?" [They should find that the R disappears.] "So, apparently, there's something wrong with your right eye...it's blind in one area. Try this, now, with your left eye." [The L disappears.] Point out that there are many imperfections in our body...and we'll be looking at some more of them later. At this time, you might ask if anyone knows why we have those blind spots [they correspond to where our optic nerves exit the eyeball]. If nobody knows, you could offer a few bonus points to the first person to find out, write it down, and hand it in, giving the source of his/her information.

Until you find some more biological items, here are some more physical science "events":

1. Set up a large tube or box with four holes on the sides (two on one side, one several inches above the other, and likewise on the other side). Insert ropes through the holes and knot their ends. Set it up so that pulling on the upper rope-end will move the opposite rope end toward the tube, but pulling on the other end moves the opposite lower rope-end to move in! (or have some similar inconsistent effect). See the new NAS book "Teaching About Evolution and the Nature of Science", pp.22-23.

2. Demonstrate your "magical talents" using a "Hooey Stick". This consists of a piece of 3/8 inch doweling (about 6 inches long) with a short "propeller" attached with a nail or screw at one end (1/4 inch doweling x 1 1/2 inches long), and about a dozen notches filed or cut along the larger doweling. A third piece of doweling, 1/4 inch x 5 inches long, is rubbed vigorously back and forth across the notches. This should cause the propeller to rotate rapidly. Upon your vocal command "Hooey", [and a subtle change in your rubbing technique], the propeller suddenly stops and reverses direction! Magic! This delightful little device has been presented in this context (along with an intriguing little story) at recent NABT conventions by talented ENSI fellow John Banister-Marx (see also his "Varves" lesson in the evolution section on this site).

3. Do a clock-reaction ( more "magic"!). Here's one recipe which works nicely. Your chemistry teacher may know of others. (This one is from "Magic With Chemistry" by Edward L. Palder, Grosset & Dunlap, 1964):

Effect: Two colorless liquids are mixed and remain colorless. Suddenly, after a definite lapse time, they change in a flash from a colorless solution to one looking like ink. [All of this is much enhanced with a clever little story you can make up, fitting into your current topic, or your school colors, etc.; practice so the change occurs at the appropriate moment in your story. The timing is temperature- and concentration-dependent, so try varying those parameters. Have fun with it.]

Materials: Make the following solutions:
(1) 12.5 g concentrated sulfuric acid dissolved INTO 125 ml distilled water. (BE CAREFUL, THIS IS HOT STUFF; Remember, always pour the ACID INTO the water, CAREFULLY, not the other way around. Use goggles, face shield, rubber gloves and apron. Be sure to label containers clearly).
(2) 2 g potassium iodate dissolved in 1 liter distilled water.
(3) A solution prepared by dissolving 2 g soluble starch in 500 ml boiling distilled water, then adding 0.4 g sodium bisulfite and 5 ml of the sulfuric acid solution (solution no. 1 above).

What to Do: Thoroughly mix equal amounts of solutions 2 and 3 by pouring them back and forth once or twice from beaker to beaker. After a lapse of several seconds, the colorless liquid changes in a flash to the color of dark ink.

NB: There are several similar kinds of "time-controlled" reactions, involving different colors (like red, yellow, white, etc.). Enjoy, but be very careful, as they generally use hazardous materials. Not for students to make or use...just for you to make and demo. Certain solutions need to be made fresh, so can't be saved from year to year. Experiment to see which ones can.















 1. Magic shops (and some toy shops) and magic books are always rich resources for finding discrepant events which are large enough to show the whole class, and easy enough for you to learn. Build your own repertoire. It's especially useful if you can do a different trick for different course topics, e.g. a disappearing egg trick for your reproduction unit, or using dice, card, or coin tricks to open a genetics unit (probability events).

2. For a list of links to a great variety of illusions, see our new lesson in which students INVESTIGATE the CAUSES of ILLUSIONS: "PERCEPTION IS NOT ALWAYS REALITY."

3. An example of a nice illusion is the "Table Stretcher" at the end of this lesson (pdf). Copy the line drawing of two tables, and make two overhead transparencies from that copy. Show one sheet on the overhead to your class. Point out (or ask if students notice) that one table is clearly long and narrow, while the other one is almost square. Tell them that you have "amazing powers" and can strrrretch one table top to fit the other. Then place the other identical transparency on top of the first, and slooowly rotate and shift it so that table A on the top transparency fits table B on the bottom transparency, making sounds and motion to suggest you are strrrretching the plastic! Very effective. The interesting question is "why is this an illusion?" "How does it work. Perhaps some of your students could form some hypotheses, then carry out investigative studies to test those hypotheses.

Remember, "Perception is not always reality". Much of the power of science is that it can cut through the misleading perceptions we experience (such as the sun's daily arc across the sky), and open up whole new worlds of reality. Illusions are a fun way to frequently remind your students of this feature of science. In fact, try our NEW LESSON in which students INVESTIGATE the CAUSES of ILLUSIONS: "PERCEPTION IS NOT ALWAYS REALITY."

4. Do the "Phantom Tube" demo, as described in Teaching About Evolution and the Nature of Science. Unfortunately, this one doesn't work too well, so get the detailed instructions for making and demonstrating a Phantom Tube that works.. This is a Flinn's Chem Fax, a 4-page version of their puzzle tube. You pull on the strings and the students watch the other strings move up and down in surprising ways. You can walk through the entire process of science using the Phantom Tube - OR... decorate your Phantom Tube with mystical figures and present it with flourish as real "MAGIC" (see example at left) - then "reluctantly" let students get skeptical and critique that idea and seek a NATURAL explanation. MOST IMPORTANT: do NOT allow the students to see the inside of the tube, nor explain how it works, or even give cues. As in the Mystery Boxes, get students to use drawings to show their hypotheses (or models) of what they think the inner workings are most likely to be, and figure out ways to test those hypotheses. If anyone hits on the its essential mechanism, do NOT say "that's it!", Just ask "does it work?" If it does, it's the "Best Hypothesis so far." It's important for them to see that in science we never get to see the "answer." It's always tentative - the explanation that works best - so far. Click Here for Special Instructions.


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: unknown

2. ENSI / SENSI original developed by: : Tom Watts, Steve Randak and Michael Kimmel

3. Modified 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 page is in Adobe Acrobat pdf format in order to maintain its intended layout for showing on overhead projector. To access the page for printing and making transparencies, 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 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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