I purchased 9 pounds of buttons for a Valentine's project with the kids. I probably didn't need to purchase that many, but Discount School Supply is great for sucking me in on good deals. I ended up putting about 3 pounds into the sensory table for the kids.
I added a muffin tin for sorting by colors, shapes, size, etc. I also went through and picked out very unique buttons from the collection. I then took pictures of each button and placed the photos by the sensory table with little baggies. I told the children they could search for those buttons and see if they could find them. I found the idea from a Montessori inspired website and amplified it for our preschool students.
Well, lesson learned. I should take more time to explain why I put the muffin tin in there, but I figured we had done enough sorting that they could just explore. They did search for those unique buttons though!