A "thermal expansion and contraction" visualization experiment kit tailored for physics, materials, and mechanical courses in middle schools, universities, and vocational colleges. It is safe, quantitative, and reproducible, helping students intuitively understand linear expansion, body expansion, and material differences. Typical experimental example: Bending experiment of bimetallic strip: Aluminum steel composite strip shows significant bending after heating, verifying the principle of bimetallic temperature control switch. Negative temperature shrinkage verification: Place the test rod in a dry ice box, record the shrinkage amount, and reverse calculate the alpha value. Comparison of liquid expansion: water vs alcohol, observe the difference in liquid column rise and fall, and introduce the concept of expansion coefficient.