Teachers can use unit blocks as tools for directed learning activities, or blocks can be reserved for children's discovery learning experiences. To use unit blocks for discovery learning, children need adequate, protected space and sufficient, uninterrupted time. Given opportunities for free play with unit blocks, children progress through seven observable stages of involvement. At the first stage very young children carry blocks around the room specifically for the purpose of carrying blocks around the room. At the second stage children place blocks in horizontal rows or vertical towers. At the third, fourth, and fifth stages children bridge separate blocks, enclose space, and embellish simple constructions. At the sixth stage the child names the block construction, and it becomes the center of dramatic play. At the seventh stage preschool children reproduce actual structures with which they are familiar. Primary school students can progress to an eighth stage, first involving planning on paper and then implementing the plans with the blocks. By using unit blocks children develop language skills, self-awareness, and understanding of the physical properties of objects. Additionally, teachers can directly and indirectly introduce vocabulary words, such as those contained in the Peabody Picture Test, into the context of block play. (Author/RH)