PreK & Up. These clever pebbles are an ideal tool for building interest in letters and sounds in a wide variety of contexts. Appeal to children's natural instinct to explore, investigate, sort and collect. Looking and feeling like real rocks, these pebbles are great for learning in the sand, in the water and outdoors. Ideal for early word building. Each set includes a storage container and teacher's guide. Set of 26 pebbles. Pebbles are approximately 1 1/2" in size.