These students' clocks demonstrate excellent reasoning skills. They proficiently uses theorems to determine the calculations needed to solve real-life scenarios involving trigonometry.

这是4~8年级的小朋友在苹果电脑的 Xcode 开发环境中用 Swift 编程语言实现的 iOS 应用。可喜的是，小朋友无论大小，都学会了最基本的三角函数。

This 4th grader draws his sketch on a whiteboard.

He polishes his clock like following eventually.