The document provides background information on tangrams, including:
- Tangrams originated in China as furniture pieces that people later used as puzzles by forming shapes with 7 wooden blocks.
- They were introduced to the Western world in the early 1800s and became popular.
- Mathematicians later proved there are only 13 possible convex shapes that can be formed with the 7 pieces.
- Traditional tangrams used materials like stone, bone or wood, while modern sets often use plastic.