Curriculum Laboratory

Optical Illusion Puzzles:
The Trilogy (In the "Theme of Three")

This motivational teaching unit was created by Bill Glaister, Curriculum Laboratory Coordinator, and was "field-tested" with Mrs. Carmen Carvalho's Grade 4 class at Huntsville School in Iron Springs, Alberta. We were joined by two of my University of Lethbridge Education 2500 students, Ms. Erin Kowalchuk and Mrs. Crystal Shigemi, who very willingly jumped right into the middle of the activities. Crystal also took all the amazing class pictures you see on this webpage. Thank you also to the Huntsville School Principal, Ms. Marg Van Egmond, for making us feel so welcome in her school.

NOTE: The students' evaluations of each activity are listed at the top of each section, in italics.

According to the students, the least favorite part of the presentation was:

"I did not not like anything."

"We needed more time at each centre, to figure all the optical illusion mysteries out."


Click here for more information!

"My favourite thing was going to the five centres and saving the world from Dr. Lux Optics."

Before we can rely on you to help save the earth, you need some background information on how we see light and optical illusions. Since we may need all the help we can get, let us start with some wonder, the "wonder of three:"

I have used the "theme of three" throughout this website, as three seems like a number full of wonder. Three of anything makes a "trilogy." A triangle, which means "three cornered," also has three sides. These three triangles are full wonder, or, at least, optical illusions:

1) The "Un-Triangle Triangles:"

("Un-triangle" and Perth triangle sculpture images used with permission from Wikimedia Commons at:

There are no triangles at all in the picture, above, but your mind "fills in the blanks," from your experience. Therefore, you think you see triangles where there are none.

2) "Impossible Triangle Sculpture"smallstar

This sculpture in Perth, Australia, shows you how an "impossible triangle" is built:


smallstar3) Draw your own "impossible triangle:"smallstar

(Or, make your own "impossible triangle" sculpture.)


Proof Optical Illusions Are Important (And Useful!):

The following optical illusion speed bumps are being installed in some cities. The girl and ball are actually a 2-D painting on the road's surface, made to look like a girl on the road. It is hoped it will help drivers to slow down in playground zones:

Virtual Street Reality Art

For Your Teacher Only: How Do I Fit This Activity Into the Curriculum? (Three Excuses)

Three Objectives of website:

    1. Survey some of the best optical illusion books and try out some of their activities
    2. Browse some of the best optical illusion sites on the web
    3. Build your own optical illusion crafts

How do I fit these objectives into Alberta Curriculum requirements? (If you are a teacher, you worry about these things.) Here are three excuses:

1) Science:

The present science curriculum contains a grade 4 unit on Light and Shadows. Many of these optical illusions deal with light, color, and shadows, and a number of the illusions use mirrors to change the pathway of light. The General Learner Expectation for the Light and Shadows science unit is that "students will be able to identify sources of light, describe the interaction of light with different materials and infer the pathway of a light beam." This optical illusion unit is really designed as a motivation introduction to the wonders of light and vision. The activities could also fit into the health curriculum, in understanding the human eye and vision. The proposed new elementary science curriculum contains a grade 4 unit on Matter and Energy (Vision and Light).

2) Art:

The drawing component in art has a section on creating the illusion of depth and perspective. Many optical illusions deal with manipulating our perspective. Optical illusion activities could easily lead into a discussion of the principles of artistic illusions. This website also requires students to create their own illusion sculptures and artwork.

3) Mathematics:

Some of these optical illusions require students to use measurement and comparison to solve problems, which fits very nicely into the math curriculum, if you have a creative mind.

In any case, optical illusions are highly motivational, so this makes a great activity to introduce any of these subjects, and promote the process of inquiry, and fun, in the curriculum.

For Your Teacher Only: Resources Needed For This Web Lesson

  • This web lesson can be used with or without the actual Optical Illusion Stations, as outlined below. The actual optical illusion stations are only available if a school in Southern Alberta schedules a session with me. If this is the case, I will cover most of the activities discussed on the website. I will need 15 minutes set-up time, and there needs to be 5 flat surfaces (i.e. tables), with two of them being at least 1.5 meters X 1.5 meters.
  • Optical illusion crafts for students to make: X-Ray Tube prototype handout, Thaumatrope or "Wonder-turn craft (cardboard squares about 4 cm. across, pencil crayons, scotch and masking tape, and pencil or dowel to use as a handle, stapler), Dragon illusion craft handout. Blank paper or graph paper, one black and one coloured felt pen or pencil crayon per student, for the Op Art craft.
  • Connection to the internet, speakers, and a projector to display this website, and its associated weblinks.

Introduction to Optical Illusions And Perception

Enough talk of wonder! The only way we will be able to solve the puzzles in the five optical illusion stations, and possibly save the earth, is to use science to fight the mad scientist. You need some background information on optical illusions:

How we become aware of things around us through our senses, including seeing, is part of "perception." Our "perception" is based on a trilogy of components:

    1. information received from the physical world through our senses,
    2. our experience in interpreting them,
    3. weaknesses and limitations in our perception.

Our eyes can play tricks on us, if we can manipulate any of these components, as you will see, in the optical illusions, below.

(Image used with permission from Wikimedia Commons at:

Which square is larger in the picture, above? Test your answer by dragging the square to the right over the squares in the image. Or, better, yet, use a ruler (Make that math connection)!

Schwartz, David (2007). Where in the wild? Camouflaged creatures concealed...and revealed. Berkeley: Tricycle Press. 591.472 Sch. Poetry and flap pages conceal and reveal hidden creatures. This book is not about optical illusions, but it sure illustrates the weaknesses and limitations of our sight, and how information from the physical world is used by creatures to fool our sight, and protect these creatures from being hunted.


Mad Scientist's Optical Illusion Stations: Can You Solve the Puzzles?

"The best part was when we had to go around to the stations and figure out the mysteries."

(For your teacher only: Setup and viewing instructions for all optical illusion centres: If these particular displays come to your classroom, there needs to be 5 flat surfaces (i.e. tables), with two of them being at least 1.5 meters X 1.5 meters.)

smallstarPuzzle #1: The Mirage:smallstar

"I liked the disappearning marble because it looked like the marlble was there, but you could put your finger through it when you tried to reach it."

Mirage Optical Illusion Movie

The Mirage Optical Illusion toy is readily available at many science stores. An object appears to be sitting on top of a small mirror, but when you try to grab the object, it is not there!

Can you guess how Puzzle #1: "The Mirage Optical Illusion" works? Click on the links below to see if you have guessed correctly:

1) The solution to the Mirage Optical Illusion puzzle.

2) Detailed description of this illusion.

Mrs. Carvalho's Grade Four Huntsville students trying to solve the Mirage puzzle:



smallstar Puzzle #2: The Missing Lightbulb:smallstar

"My favourite centre was the missing lightbulb because we couldn't figure it out."

Missing lightbulb viewed from the front window:
Missing lightbulb viewed from the side window:

Missing lightbulb movie.

Imagine looking at the lightbulb, above, through the small window in the front of the Missing Lightbulb display box. Next, you look through the window on the side of the box, and you see there is no lightbulb in the light socket: it is a missing lightbulb.

Can you guess how Puzzle #2: "The Missing Lightbulb" works? Click on the links below to see if you have guessed correctly:

1) The solution to the Missing Lightbulb puzzle.

2) The Missing Lightbulb Optical Illusion is based on the Touch the Spring exhibit at the Exploratorium Museum of Science, Art and Human Perceptions, in their Science Snacks section, where teachers have adapted museum displays to the classroom.

Huntsville School students trying to solve the Missing Lightbulb puzzle, and Mr. Bill Glaister giving them some hints:



smallstarPuzzle #3: The Case of the Missing Watch and Magnifying Glass:smallstar

The missing watch and magnifying glass movie

The above picture shows a watch and a magnifying glass. You can see through and around the magnifying glass, when viewed from the front. However, if you reach into the display box from the top, there is nothing in the box!

Can you guess how Puzzle #3: "The Case of the Missing Watch and Magnifying Glass" works? Click on the links below to see if you have guessed correctly:

The solution to "The Case of the Missing Watch and Magnifying Glass."

Grade four Huntsville School students trying to solve the Missing Watch and Magnifying Glass mystery:


smallstarPuzzle #4: Do You Want to Bet That "Movies Do Not Move,"smallstar
or "Motion Pictures Do Not Have Motion?"

"I liked the galloping horse image, bcause I like solving mysteries. The horse looked like it was running, bu it wasn't!"

The following machine is called a "Praxinoscope Animation," by KidzLabs. It is a replica of a scientific invention from 1877, which shows us how movies are still made today.

Praxinoscope Movie

Can you guess how "Movies Do Not Move," or "Motion Pictures Do Not Have Motion," based on the Praxinoscope? Click on the link below to see if you have guessed correctly:

The solution to "Movies Do Not Move," or "Motion Pictures Do Not Have Motion:"

Grade Four Huntsville School students trying to solve the Movies Do Not Move mystery:


smallstarPuzzle #5): The Optical Illusion Ring:smallstar

"My favourite centre was the ring, because it always got bigger or smaller, depending on which way you turned it on your finger."

This simple Optical Illusion Ring is designed by magic inventor Rob Stiff and can be purchased through many magic or optical illusions stores. Put this ring on your finger. If you twist it in one direction, it appears to grow. If you twist it in another direction, it appears to shrink.

Ring Movie

The solution to the puzzle of the optical illusion ring: I do not have an explanation. Do you?

The Huntsville School students continue to try to solve these optical illusion mysteries:

Simple Optical Illusions From Great Optical Illusion Books

There are many excellent books that are filled with optical illusions that require very little preparation time or costly materials.  They are great to use to start off science classes on a regular basis.   I believe these types of quick and easy activities "break the ice," and can stimulate the student's natural wonder. 

Below are some of my favourite optical illusions books, and my favourite simple optical illusions from these titles. I recommend that you: 

  • do each activity,
  • have the students hypothesize as to what explanation causes the activity to work the way it does, 
  • discuss how we could test their explanation (e.g. by doing the activity in a different way, and see if the results change),
  • encourage the students to find the explanations given in the books  on their own. 

Simple Optical Illusions (Simon, 1998, p. 6, 13)
Which of the two lines in  the box to the left looks longer?  They are actually both the same size.  To get your students to work with this illusion, simply have them draw 2 lines, one vertical and one horizontal, of exactly the same length, with the vertical line bisecting the horizontal in half.  The book has some excellent hypotheses your students can test, as to why they do not perceive what is actually there.

In the illusion to the right, line AB is the same size as line BC, believe it or not!

The Floating Finger (Churchill, 1989, p. 8-9)
Have students position themselves about 1 meter away from a wall.  Have them hold their two hands in front of their face at eye level. Have them point their index fingers at each other, keeping their fingers about 2 cm. apart.  Have them focus on the wall, just beyond their fingers.  When they do this, it will appear that a tiny disconnected finger is floating in the space between their finger tips.  If the students focus on their fingers, instead of the wall just beyond their fingers, the illusion disappears.

The Wonder of Mobius Strips (McGill, 1992, p. 36-37)
Prepare three circles or bands of paper for each group ahead of time as follows.  Cut three strips of paper from a newspaper.  Tape the ends of the first one together. Tape the ends of the second one together, but give the band a half twist, before taping it together.  Do the same for the third strip, but give it a full twist.   Have the students cut each band in half lengthwise.  The first band will become two bands of equal size, as expected.  The second band becomes two bands linked together.  The third band comes out as one giant band, twice the size of the original.  The twisted bands are called mobius strips. You can also make a small mobius strip, and tell the students to color the front side of the strip one colour, and the backside a different colour.  However, they will find that this is impossible, because there is only one side to a mobius strip. While not an optical illusion, this is one of my favourite science tricks, and I couldn't resist including it here!

Cheshire Cat (Doherty, Paul and Rathjen, Donald, 1991, p. 22-1)
Have a student sit next to a white wall (STUDENT A).  Have them hold a hand mirror up to their nose, so that their right eye sees the reflection of the white wall in the mirror.  Have another student (STUDENT B) sit opposite student A, so that the student A sees the student B with their left eye.  Instruct student A to look through both eyes, and move their right hand in front of the white wall, as if erasing something off the wall.  Parts of student B's face should disappear, usually leaving student B's smile and/or eyes floating in space, without a face!  It is just like in Alice in Wonderland, where the Cheshire cat "vanished quite slowly, beginning with the end of the tail, and ending with the grin, which remained sometime after the rest of it had gone. (From Lewis Carroll's Alice's Adventures in Wonderland, Lancer Books version, 1968, p. 71)"



Browsing the Best Optical Illusion Books

Have students browse through great optical illusion books, such as the ones on the list below, and spend 10 minutes browsing the titles.  Each group should be prepared to share at least on amazing or unbelievable illusion they found.


Great Optical Illusion Books

Most of the books featured throughout this handout were selected by searching in the Curriculum Laboratory using the subject heading, "optical illusions."  As well, the author browsed the library shelves under the Dewey Decimal numbers 152.1 and 612.8. You can find optical illusion books in your own library in the same way.

Anno. Mitsumasa (1980). Anno's magical ABC. New York: Philomel Books. 421.1 Ann. This title employs anamorphosis, which has been used by artists for centuries. In Japan, anamorphic paintings were created that could only be viewed correctly when reflected in the bright blade of a samuri's sword. In this title, the images can only be seen correctly in the supplied cylindrical mirror. An anamorphic painting. Anamorphic optical illusions.

Ausbourne, Robert (2007). How to understand, enjoy, and draw optical illusions. Pomegranite Communications. 152.148 Aus.

Churchill, Richard (1989). Optical illusion tricks and toys. New York: Stirling Publications. 152.148 Chu.

Cobb, Vicki (1999). How to really fool yourself: illusions for all your senses. Toronto: John Wiley and Sons. 612.8 Cob.

Diagram Group. Visual tricks. Sterling Publications. 152.148 Vis.

DiSpezio, Michael. Optical illusion experiments. Sterling Publishing. 142.148 Dis.

Edwards, Wallace (2007). The painted circus: P.T. Vermin presents a mesmerizing of trickery and illusion guaranteed to beguile and bamboozle the beholder. Toronto: Kids Can Press. 152.148 Edw.

Exploratorium. Teacher Institute (1991). The Exploratorium science snackbook. San Francisco: Exploratorium. 502 Exp.

Friedhoffer, Bob (1996). Magic and perception: the art and science of fooling the senses. New York: Franklin Watts. 793.8 Fri.

Funston, Sylvia (2000). The book of you : the science and fun of why you look, feel, and act the way you do. New York: Beech Tree Books. 155.2 Fun.

Gold, Carol (1991). Science express. Kids Can Press. 507.8 Gol.

Illusionworks Staff. Amazing optical illusions. Firefly books. 152.148 Ama.

Jennings, Terry (1996). 101 amazing optical illusions: fantastic visual tricks. New York: Sterling Publications. 152.148 Jen.

Kay, Keith. Optical illusions. Sterling Publications. 152.148 Kay.

McGill, Ormond (1992). Paper magic: creating fantasies and performing tricks with paper. Brookfield: Millbrook Press. 793.8 McG.

O'Neill, Catherine (1987). You won't believe your eyes! National Geographic Society. 152.1 One

Sato, Koichi (1994). Optical illusions coloring book. Dover Publications. On order.

Schwartz, David (2007). Where in the wild? Camouflaged creatures concealed...and revealed. Berkeley: Tricycle Press. 591.472 Sch. Poetry and flap pages conceal and reveal hidden creatures. This book is not about optical illusions, but it sure illustrates the weaknesses and limitations of our sight, and how information from the physical world is used by creatures to fool our sight, and protect these creatures from being hunted.

Seckel, Al (2000). The art of optical illusions. Carlton Books. 152.148 Sec.

Seckel, Al (2006). The science of visual perception. Firefly Books. 152.148 Sec.

Seckel, Al (2006). The ultimate book of optical illusions. Sterling Publications. 152.148 Sec.

Simon, Seymour (2003). Eyes and ears. New York: HarperCollins. 612.8 Sim. Describes the anatomy of the eye and ear, how those organs function and some ways in which they may malfunction, and how the brain is also involved in our seeing and hearing.

Simon, Seymour (1998). Now you see it, now you don't : the amazing world of optical  illusions. New York : Morrow Junior Books. 152.148 Sim.

Simon, Seymour (2000). Out of sight : pictures of hidden worlds. New York : SeaStar Books. 612.84 Sim. Shows pictures of objects which are too small, too far away, or too fast to see without mechanical assistance such as microscopes, telescopes, X-rays, and other techniques.

Wick, Walter (1998).  Walter Wick's optical tricks. New York ; Toronto : Scholastic. 152.148 Wic. Presents a series of optical illusions and explains what is seen.

Wiese, Jim (2000).  Head to toe science : over 40 eye-popping, spine-tingling, heart-
pounding activities that teach kids about the human body.  New York : Toronto : John Wiley & Sons. 612 Wie. Introduces the circulatory system, muscles, digestion, senses,  and other body parts and functions through a collection of activities and experiments which can be developed into science fair projects.


A Trilogy of Optical Illusion Crafts: Amaze Your Friends and Family!

Build these three optical illusion crafts, and share them with your friends and family.

1) X-Ray Tube Prototype (Gold, 1991, p. 14)"

Our research laboratory is experimenting with a prototype, or first model, of a X-Ray Tube, and we would like you to help us test it. Print out the X-Ray Tube prototype and color it above the "Hi-Tech Fastener" line. Roll it into a tube, about 2 cm, across.  Look through the tube with your right eye.  Hold your left hand beside the tube, with your palm facing you.  Slide your hand towards your face, with both eyes open,  looking  straight ahead.  You should be able to see right through your hand!

Mr. Bill Glaister and Mrs. Carmen Carvalho are amazed by this piece of technology as they use it to look right through their hands:


2) Thaumatropes or "Wonder-turns:"

Cut out a square of cardboard about 4 cm. across.  Draw a fish on one side and a bowl on the other.  Tape the disk to the top of a pencil, and whirl the pencil rapidly in your hands.   The fish will appear in the bowl. You could try a bird and a cage, as well.  Another Thaumatrope craft.

3) Dragon Illusion:

Create a paper dragon (Click on download on this page). If you squint a little, close one eye, or perhaps put him in a display box, your mind assumes his nose sticks out and not in. Therefore as you move side-to-side, or up-and-down, his head appears to move as if the dragon is following your every move. Filming him brings this illusion alive.

Bonus Activity: Op Art

"My favourite thing was the Op Art craft, because it was the first time that we did a craft about an illusion. It was creative and very fun."

According to the Wiktionary Op Art is a type "of abstract art that uses geometric shapes and vivid colours to create optical illusions, such as an illusion of movement." These types of art can also include hidden images, pattern, or warping.

This bonus art activity gets students doing their own Op Art.

1) Browsing different types of Op Art.

2) Oodles of Art, produced by an elementary teacher, has a very nice Op Art activity. Students can either use their rulers to create the grid paper she talks about (simply use the width of the ruler to draw parallel lines across the page, and then perpendicular lines, to make squares on the paper), or use this completed grid paper for the activity.


For this activity, the "Oodles of Art" hints and helps are, well, helpful:

  1. Fill in the grid paper lines with felt pen.
  2. Add some of your own geometric shapes, such as circles on the page. Some of them can go off the edge of the page.
  3. Pick one coloured felt pen, and fill in every other square with a colour.
  4. Go slow and think first: no coloured shapes should be side-by-side, but should be corner-to-corner with each other.
  5. My hint: Start colouring in the upper left hand corner, and move left to right with your colouring, just like you were reading a book.


Op Art

Finished Op Art Samples:


The Best Optical Illusions on the Web

Below are some of my favorite optical illusion sites. I would like to share my top 9 (three X three) optical illusions from these sites (NOTE: For the eChalk illusions, you may have to scroll down their list of illusions, and click on the correct title):

My favorite illusions are taken from these websites, which contain many more illusions for you to explore:


Created by Bill Glaister, Curriculum Lab Coordinator, December 2009. Updated June 2010. Thank you to Grade Four Teacher, Mrs. Carmen Carvalho, and her students, for their feedback on all the activities, and their wonderful artwork. Thanks also to my Ed. 2500 students from the University of Lethbridge, for working with all of us:

Mrs. Carmen Carvalho, Grade Four Teacher at Huntsville School

Mrs. Crystal Shigemi, Ed. 2500 student and photographer for the class visit

Ms. Erin Kowalchuk, Ed. 2500 student

Mr. Bill Glaister, Curriculum Laboratory Coordinator

(There is a rumour going around that Bill Glaister and Dr. Lux Optics are one-and-the-same-person. This is not true, though both are good looking, don't you think?)

Dr. Lux Optics, infamous mad scientist
(Thank you to Mrs. Carvalho's grade four students, who saved the earth from his evil devices!)