When you use this teacup, you can pour water without any problems partway. But water will spill from the teacup if you pour too much water greedily. Let’s check how to make it and its mechanism.

Things which you need

• A plastic cup or a paper cup
• A straw with bellows
• A rubber band
• Scissors
• A gimlet or an awl
• Additional Materials : Vinyl tape or a glue gun

How to make

For more detailed instructions, please watch the video above.

1. Fold the straw with the bellows part, and cut its longer side so that it's about 1 cm longer than the shorter side.
2. Wrap a rubber band around the straw so that it is kept folded. (Also you can use vinyl tape or glue gun in this step.)
   ATTENTION : Please be careful when you use sharp pointed tools like a gimlet or an awl!
3. Make a hole in the bottom of a cup where you can barely put the straw.
4. Put the longer side of the straw through the hole you made. It should stick out of the hole a little.
5. If you have vinyl tape or a glue gun, it's better to fill the gap with it between the cup and the straw.

How to play

Pour water in the cup! You can pour water without any problems partway, But… if you pour too much water greedily, water will spill from the cup. This cup teach you a lesson that if you grasp all, you lose all.

コラム「アルキメデスと王冠おうかん」

古代こだいギリシャの科学者として名を遺のこしているアルキメデス。彼かれは、王様おうさまから、職人しょくにんの作つくった王冠 おうかんが純金じゅんきんで作つくられたものか、王冠 おうかんを壊こわさずに確たしかめよ、という命令めいれいを受うけます。その王冠 おうかんには金きんをいくらか減へらして代かわりに銀 ぎんを混まぜてあるという告発こくはつがあったからです。

職人しょくにんに渡わたした分ぶんと同量どうりょうの金塊きんかいと比くらべてみても、王冠 おうかんの重おもさは同おなじでした。その当時とうじ... 続つづきを読む