For this you need a sewing machine, sewing machine serger, buttons and polyester fabric. The ones shown were made from polyester pants from Goodwill.
Cut the polyester fabric into 2.5" strips in a variety of lengths. Using a sewing machine serger, serge around each side of the strips. Now the fabric
will not unravel. Now use your sewing machine and make a button hole on one end of the fabric as shown. Sew a large button on the opposite end.
Now keep making them varying the lengths.
To play, give the pieces to the children. Have them button them together to make a piece the length of the room. Have them button the pieces
together to make letters of the alphabet. If you notice in the photo a letter
Y was made. To do this, more than one strip was buttoned on to the same
button. These are great for making shapes. Children have to find four the same length, and button them together to make a square. Point out if
the pieces aren't the same length, then it isn't a square.
Be sure to sew your buttons on carefully to ensure that they don't get
loose and become a choking hazard.
This is a project that is fun to do together with a colleague.