Mind-blowing optical illusions introduce students to positive and negative space using basic supplies; paper, scissors and glue. 

optical illusion samples:

https://drive.google.com/file/d/1RrjRMERVczji7deBtLQ398lgl2TOqOEg/view?usp=sharing

student samples:

https://drive.google.com/file/d/1WBhNaro7_45ZmSsoWb56lK29P0ZekD9Q/view?usp=sharing

step-by-step pictures:

https://drive.google.com/file/d/1XAtMT8Di0RLrDrfhZ1Bt-YJLnjBZj5wl/view?usp=sharing