Unlike drawing an artistic picture, children need to draw optical illusions exactly as described. Because the artist is trying to trick other people’s eyes into seeing differences that aren’t there, the illusion won’t be an illusion if lines that are supposed to be the same size (but look like they’re not) are really different sizes.
Materials for Drawing Visual Tricks
Use a sharp pencil to draw light lines that can be erased. If desired, go over the lines with a black or blue pen. The child should select a pen that allows him to draw lines of the same thickness and that avoids blobs.
A ruler is necessary to draw straight lines. It doesn’t matter if a child knows how to read a ruler, although being able to identify inches is useful. As long as she draws lines that have to be the exact same size the same size, it doesn’t really matter the specific length. A glass or plastic cup will give the child two circles. For a smaller circle, use the cap off a water or milk jug.
Line Length Visual Illusion
At the top or bottom of a piece of paper, write, “How much longer is line ‘a’ than line ‘b’?” Draw two horizontal lines, both four inches long, approximately four inches away from each other. Label one line ‘a’ and the other line ‘b’.
For line ‘a’, draw a sideways “V” on each end, pointing the “V” or arrow toward the line (so the points are actually touching the line). For line ‘b’, draw a sideways “V” or arrow on each end, point the arrow away from the line (again, so the points are actually touching the line). For an even more exact illusion, measure the “V” shapes so they are all the same length.
Circle Size Illusion
At the top or bottom of a piece of paper, write, “Which circle has the greater diameter?” Use the opening of a cup held so it is touching the paper as the template to draw two circles approximately two inches (or three finger-widths) apart. Draw twelve arrows evenly spaced on the inside of one of the circles, so the arrowheads point inward. On the other circle, draw twelve arrows evenly spaced around the outside of one of the circles with the arrowheads pointing outward.
Visual Trickery
At the top or bottom of a piece of paper, write, “Which is the longest object in this picture?” Draw six-to-eight three inch lines over the page. The lines should not overlap. However, the lines can be drawn horizontally, vertically, or diagonally at any angle.
Add some details to the lines so that they look like paper clips, safety pins, narrow rectangles, triangles, etc. Avoid changing the length of the lines as this is the illusion! Add a few more lines, this time making certain that they overlap other objects. Again, convert the lines into objects.
Circle Comparison Teaser
At the top or bottom of a piece of paper, write, “Is the outside circle of ‘a’ smaller than the inside circle of ‘b’?” Set the bottom of the glass against the paper. Trace the circle twice, keeping the two circles about two inches, or three finger-widths apart from one another. Take the bottle cap and set it inside of one of the circles and trace it. Label the inside of these circles ‘a’. Flip the glass over and set the open end around the other circle and trace it. Label these circles ‘b’.
In these optical illusions, the brain interprets what the eye sees in a way that differs from measurable reality.
 |
 |
 |
 |
