# THE BULGE – Creating Optical Illusions

Students use coloured pencils and The Bulge worksheet to create an optical illusion of 3-dimensional spheres on a 2-dimensional surface.

60 Minutes

Mathematics
Visual Arts

#### Vocabulary

2-dimensional 3-dimensional op art optical illusion

#### Materials

Rulers Erasers Photocopies of Bulge Worksheet Scissors

## Steps

### Step One

1. Cut out the circles to use as tracers.

### Step Two

1. Decide how many circles you want to use in your design.
2. Arrange the circles in the square and use a pencil to trace around them.

### Step Three

1. Use a ruler to draw horizontal and vertical lines to connect the dots on the sides of the square.

### Step Four

1. When you come to the circle gently curve the line as if you are moving over the surface of a sphere, then continue to the other mark in a straight line.

### Step Five

1. Once all the lines are drawn you may want to go back and double them.

### Step Six

1. Colour in the spaces using a variety of coloured pencil techniques.

## Learning Goals

Students will be able to:

1. Create an optical illusion of 3-dimensional spheres on a 2-dimensional surface.
2. Use coloured pencil techniques to create the illusion of depth.
3. Follow written instructions to accurately complete an op art design.

## Extensions

1. Have students apply their understanding of how to create a bulge optical illusion by making an op art work using different media such as construction paper crayons, tempera or acrylic paint, watercolour pencils, or markers.

## Prepare

1. Prior to this lesson you may want to have your students complete the Coloured Pencil Techniques worksheet available on this website.
Coloured Pencil Techniques
3. Copy the circle template on cardstock paper, and the instructions on regular copy paper.
Vasarely
Vasarely2
Tousignant
Riley

## Introduction

1. Display the op art images.
2. Discuss the works and make a list of characteristics of the art, for example,
- although the works are flat they fool the eye into thinking they are 3-dimensional, or actually moving
- a mathematical form of art based on geometry
- non-objective
- uses contrasting colour, line and shape to create a sense of movement
- uses perspective
- positive and negative spaces are equally important
3. Introduce the challenge.

## Activities

### The Challenge

1. Create an optical illusion of 3-dimensional spheres on a 2-dimensional surface.
2. Use coloured pencil techniques to create the illusion of depth.
3. Follow written instructions to accurately complete an op art design.

### The Process

1. Guide students through the steps outlined in worksheet.
2. Establish success criteria with your students, for example,
careful measurement
- accurate op art bulge design
- effective use of colour combinations
- paper in good condition
3. Observe students as they work.
4. Encourage them to share and expand on each others' ideas.
5. Provide individual assistance and encouragement.

## Sharing

1. Place students in small groups and have them share thoughts about the work.
2. During the discussion include references to:
colour - how colour combinations and shading affect the overall impact of the work
-  technical accomplishment - how condition of paper, careful measurement and attention to detail affect the overall impact of the work
3. Ask students what they found satisfying about doing this project and why.
4. Ask them what was difficult about doing this project and why.

## Assessment

1. Observe students as they work – thoughtful focus, discriminating, seeking more information, elaborating, experimenting
2. Observe students as they discuss the art works – active listening, insightful contributions, supporting ideas with evidence found in the artwork and from personal experience.