Open up your 1 yard of flannel fabric to remove any creases or folds. Hang it over a chair, or iron it on a low setting.
Lay the flannel on a large work surface, such as clean carpet. Place the 20-by-24-inch or larger prepared canvas in the center of the flannel with the canvas facing down. This type of prepared canvas is used by artists to paint on, and is already stretched onto a frame of wooden bars. You want the wooden bars facing up.
Wrap the flannel over the sides of the canvas. Trim excess flannel with fabric shears, leaving enough fabric so it covers the prepared canvas and the wooden bars.
Staple the flannel firmly and taut onto the wooden bars of the canvas, starting in the center of each side of the frame. Once you make one staple into the center of each bar, add more staples around the wooden bars until they are approximately 1 inch apart.
Fold over the corners of the flannel so they look smooth and staple them down. Flip over the flannel board to use. Cut out felt animals and shapes according to your lesson plans. Press them onto the flannel to stick.