第二十三课

 23 hourglass 沙漏

Questions and speculation问题与猜测

Why did the hourglass leak in three minutes? 为什么这个沙漏刚好3分钟漏完呢？

What does the hourglass? 沙漏有什么作用?

Inquiry and practice. 探究与实践.

Know the hourglass. 认识沙漏。

How long does it take to flow all the sand into the quicksand pool below? 上面流沙池的沙子全部流到下面的流沙池中，需要多长时间?

pore细孔

Flow sand pool流沙池

sand沙

The hourglass, also called sand clocks, is a tool to measuring time. 沙漏也叫沙钟，是一种测量时间的工具。

●Make an hourglass制作沙漏。

Jelly box果冻盒

silver sand 细沙

awl锥子

glue胶水

pencil铅笔

ruler直尺

hardboard硬纸板

Watch safety when using cones. 使用锥子时要注意安全。

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Test the hourglass测试沙漏。

I tested this hourglass repeatedly to timing …我反复测试了这个沙漏，可以计时....

The sand flowed too fast. 沙子流得太快。

●Improve the hourglass to keep your sand full for 1 minute. 改进沙漏，让自己的沙满计时1分钟。

How to make the hole get smaller? 怎样让孔变小呢?

Sand sand be sand sand sand可以将沙子换成.....

Time it up with an hourglass to see who jumps more用沙漏计时，看谁跳得多

Expansion and Innovation拓展与创新

Make a creative hourglass. 做个创意沙漏。

I also want to do it. 1: 我还想做.个.....