A word mask is a reading tool that helps students find small words in bigger words.
These words are found in a "word wall" which is a collection of words displayed in large letters on a wall or other large display area in the classroom.
Place the word mask over a word and students will discover the smaller words.

Examples :  in classroom there is class and room (classroom)
                     in  golfer there is golf (golfer)

How to build a word mask
Use an empty box of facial tissues.
Open the box ends.
Flatten the box.
Remove the ends of the box.
Remove the bottom of the box.
Place the bottom of the box to the side.
Remove cellophane paper from the box.
Trace a square around the box cover opening.
Fold the ends of the box to the edge of the box cover opening.
Staple the edges along the fold line of the box.
Slide the bottom of the box along the stapled tracks.

Watch the video to better understand the procedure.