1.is the core part of the steam , so habits is also commonly refers to. Is a major part of the engine cylinder, but also the whole vehicle's power source. 2.Basic principles: steam engine, tubular liquid container, heating and cooling device set respectively in the heating and cooling section of the liquid container, and the output unit is connected to the liquid container, so that the output device through the liquid 3. comprehensive and detailed: product based on the model, stress field, multi-dimensional learning and experience 4. image, product design pays attention to "hands-on science", to cultivate children's interest in science, hands-on is conducive to the memory of knowledge and master Premium lab equipment made of high-grade durable material, safe and sturdy for long-term use in school, lab, and home science experiments.