任務Task
Design and make a catapult and then try to win a “catapult competition”.
投石器是如何運作的？How does a catapult work?
在古代，投石器是戰爭中使用的簡單機械。投石器利用了能量可以從一種形式轉換為另一種形式，並可從一個物體轉移至另一個物體的原理來運作。
當你使用投石器投擲物件時，額外的能量會加入其中。這種能量是儲存在橡皮圈或投石器繩子中的勢能。當你把要發射的物體（如石頭）放入桶中，並讓投石器的臂部移動時，儲存的勢能會被釋放並轉化為發射物體的動能，使它能拋射出去。
In ancient times, a catapult was a simple machine used in war. A catapult works on the principle that energy can be converted from one form into another and transferred from one object to another.
When you launch a catapult, extra energy is stored in the string or rope of the catapult as potential energy. When you put the launched object (like a stone) in the bucket and let the arm go, the stored potential energy is converted into kinetic energy of the launched object, which will then fly through the air.
第一部分—設計和製作投石器Part A—Design and make a catapult
1.
在互聯網搜尋製作投石器的不同方法。列出你的設計所需的物料。
Search the Internet for different methods of making a catapult. List the materials your group will choose to make it.
2.
在以下的空位內繪畫你的設計，並在各部分加上標註。試簡單描述製作投石器的步驟。
Draw your design below. Label all the parts. Also, briefly describe how you will make the catapult.
3.
寫出你的設計的參考來源。
Write the source(s) of reference that your design is based on.
4.
和組員合作完成投石器。
Collaborate with your group members to make the catapult.
第二部分—投石器比賽Part B—Catapult competition
用你製作的投石器在課堂上進行比賽！
Use your own catapult to take part in the following games!
比賽1Game 1
每組需要使用自己的投石器來發射橡皮擦，能夠使橡皮擦飛得最遠的組別獲勝。
你會考慮甚麼因素來增加獲勝機會？
Use your own catapult to launch a rubber. The group which can make the rubber fly the farthest wins.
Which factor(s) will you consider in order to win the game?
比賽2Game 2
每組需要使用自己的投石器，並自行決定發射的物體，然後盡可能擊落最多的汽水罐。能夠擊中最多汽水罐的組別獲勝。
你會考慮甚麼因素來增加獲勝機會？
Use your own catapult and decide the launched object, in order to hit down as many soft drink cans as possible. The group which can hit the largest number of cans wins.
Which factor(s) will you consider in order to win the game?
第三部分—評價和改良Part C—Evaluate and redesign
3.
你認為哪一組的設計是最好的？寫出他們的設計的兩個優點。
1.
Share your experience in making the catapult with your classmates.
2.
Ask your teacher to evaluate your catapult using the following Grading Rubric:
3.
Which group’s design do you think is the best? Write TWO advantages of this design.
4.
What modifications can you make to your catapult?
5.
Submit Student’s Worksheets to your teacher after the lesson.
第四部分—附加資源Part D—Further resources
你可以在Scratch試玩以下免費的投石器遊戲。如果你熟悉編程，也可以自行修改遊戲。
You can now play free catapult games on Scratch. If you are familiar with programming, you can also modify the games.