Interesting scientific experiments in the cold winter-be careful to be safe, don't play big.

Low temperatures swept through most cities in the United States and Canada, and schools in several cities canceled courses. For those young people who leave their parents, it is only indoors. If you want to have some fun with the kids, here are some small pleasures (including a little science education) that take advantage of the cold weather ...

LiveScience has collected some interesting experiments, ranging from making frozen bubbles to making your own snow (there's an experiment to make sure kids don't try it easily).

Children like bubbles. Although summer is usually a good season for Da Pao, we also have a way to play it in winter. If the temperature outside is low enough (when you write this article, 零下9到12华氏度, 零下11摄氏度), the bubbles will freeze up. Then you can crack the bubbles that froze before they landed on the ground. The shape of the bubble looks like a transparent crystal, and a cracked bubble is a bit like a cracked egg shell.

Make your own maple candy. Pour the hot butter and syrup together, and according to the recipe, cool it down in the snow and it will turn into a hard maple toffee. Full of delicious yo ~

Well, maybe they're not magical, but they're still amazing for kids, and they're simple to make. It just needs to blow up a balloon and tighten it up and put it outside and watch it shrink. Then bring it back indoors, let the balloon heat up and look at it again (this can intuitively understand the volume of the gas change.) The volume of the gas shrinks under cold conditions, and the density becomes larger. The gas volume expands and the density decreases under the condition of high temperature.

If the outside is cold enough, you can bring some boiling water and spray them in the air (make sure they will be blown away), and the boiling water will freeze into the snow in an instant. The test site in the video is Wisconsin State, the temperature is 零下21华氏度 (零下29摄氏度) The cold wind blows the temperature is 零下51华氏度 (零下46摄氏度).

How does boiling water become snow? Cold air contains less water vapor than warm air, and there is a lot of water vapor in boiling water (which is what you see from the pot). When the hot water enters the cold air, the air contains more vapor than its limit, the vapor is attached to the small particles in the air, crystallization into snow.

The experiment is to make sure that children do not try it lightly, and that it is foolish to bet their tongues to lick the frozen flagpole. Maddie Gilmartin, a 12-year-old from New Hampshire State East Kingstown, made a bold attempt. As it turns out, her tongue was frozen solid. Her parents tried to blow a hot air on her tongue and poured warm water to let the flagpole "let go". Finally, with the help of the medical staff, she was saved. Although the tongue is expected to recover, it may be swollen for 6 months.

Why is that? Because the tongue is warm, when it touches a cold flagpole, the flagpole cools the tongue by lowering its temperature, which causes the body to deliver more heat to the colder parts. But the conductivity-rate metal flagpole means it absorbs more calories faster than the body's feeding the tongue. As a result, the water in the pores of the tongue is frozen with metal. All right, then you're going to have a big game.