Construction set:The Original Anchor Blocks No. 8, Manual No. 2

In 1840 Friedrich Froebel, pioneer of the kindergarten movement, developed a building block set made of wood. He believed that the process of creating a three-dimensional structure from a two-dimensional plan would help develop a child's mind. However, the lightweight wooden structures children build often collapsed before they completed their constructions. By 1875 German brothers Otto and Gustav Lilienthal had created an alternative to unstable wooden blocks, manufacturing precisely-shaped building blocks from quartz sand, powdered chalk, and linseed oil. They called the new product Anker Blocks (known to Americans as Anchor Blocks). The brothers sold the design to entrepreneur Friedrich Ad. Richter, who immediately applied for a patent and established a factory for the sole purpose of producing Anchor Blocks. The block sets enjoyed immense popularity, pleasing toddlers, children, and adults alike. American manufacturers, such as La Velle and A. C. Gilbert, soon began making their own versions of the well-loved building blocks, and Anchor Blocks remain in production into the 21st century.