光沿直线传播
Light Travels in Straight Lines
认识光沿直线传播，并能利用这一知识解释我们怎样看见物体，以及为什么影子的形状和遮挡物体的形状一样。
Recognise that light appears to travel in straight lines and use this to explain how we see objects and why shadows have the same shape as the objects that cast them
学习证据 / Evidence
- 说出并演示光沿直线传播（例如：不能绕过拐角看到物体，激光笔的光线）。
- 利用光的直线传播，解释为什么影子的轮廓形状与物体相同。
- 绘制光线图，展示光从光源发出、被物体挡住、在屏幕上形成影子。
- State and demonstrate that light travels in straight lines (e.g. can't see around corners, laser pointer)
- Use straight-line light to explain why shadows have the same outline shape as the object
- Draw ray diagrams showing light travelling from source, being blocked by object, creating shadow on screen
评估问题 / Assessment
{{name}}能利用光沿直线传播的道理，解释为什么手的影子看起来是手形吗？
Can {{name}} explain why a shadow of a hand looks like a hand shape, using the idea that light travels in straight lines?