Collect small pieces of cloth and paper of different textures:
velvet, sandpaper, cellophane, burlap, silk, tissue.
You can go to a fabric store and ask for swatches of different fabrics for free.
Then you could put them in a shoe box and have them pull out a piece of fabric one at a time and describe it. Is it rough and bumpy and brown? Is it smooth and silky and pink?
If you have older children try putting a cover on the box and have them reach their hand in to feel the object and have them guess which fabric piece it is.
I think it would be really fun to get larger 1' x 1' square pieces of a variety of textured fabrics, sew them together and make a texture quilt. Wouldn't that be fun in a classroom?