第十五课

Unit 5第五单元

Common forces常见的力

1.Pull the bow and shoot arrows, float in the water, and move forward. When you do these actions, do you feel the existence of force? Let's study together.

拉弓射箭，水中漂浮，迈步前行....当你做这些动作时，你是否感受到力的存在? 让我们一起研究力吧。

 fifteen15

Floating and sinking浮和沉

1. The boat can float on the water; if we put in a swimming circle, we won't sink into the water. Why is that?

小船能浮在水面上;我们套上游泳圈就不会沉入水中....这是为什么呢?

Activity process活动过程

2. Are they sinking or floating in the water? 它们在水中是沉还是浮?

3. Press, I feel...按一按，我感觉....

4. An object is subjected to a vertical upward force in the water. A force like this is buoyancy.

物体在水中会受到竖直向上托起的力。像这样的力是浮力。

5. Will objects sinking in water be buoyant by water?在水中下沉的物体会受到水的浮力吗?

6. Immerse the hook code in water. Does the length of the rubber band change compared with the previous one?

把钩码浸入水中，橡皮筋的长度与之前相比有变化吗?

7. What are the applications of buoyancy in life?浮力在生活中有哪些应用?

8. The fish was bleached...鱼漂利用了....

Outreach activities拓展活动

9. Look for information and make a float.查找资料，制作一个浮沉子。

10. sixteen16Learning in springs弹簧里的学问

11. What happened to trampoline when playing trampoline? When pulling rubber band, what is the feeling on the hand?

玩蹦床时，蹦床发生了什么变化?拉橡皮筋时，手上有什么感觉?

Material package材料包

12. Sponge, cotton, foam, eggs, etc海绵、棉花、泡沫塑料、鸡蛋等

Activity process活动过程

13. Play, what to find? 玩一玩，有什么发现?

Thinking Navigation思维导航

14. What happens to the length of the spring when pulling the spring? How does the hand feel? What changes to the spring after release?

拉弹簧时，弹簧的长度发生了什么变化?手有什么感觉?  松手后，弹簧有什么变化?

15. 2.When pressing the spring, what do you find?压弹簧时，有什么发现?

16. When the spring is stretched or compressed, it produces a force to return to its original shape.

17. A force like this is elastic.

弹簧被拉伸或压缩时，会产生一种要恢复到原来形状的力。

18. A force like this is elastic.像这样的力是弹力。

19. Where does life use elasticity?生活中哪些地方利用了弹力?

20. I also know...我还知道...

21. Design an egg protector. 设计一个鸡蛋保护装置。

22. My method is...我的方法是...

Outreach activities拓展活动  

23. Make a elastic toy. 制作一个弹力玩具。