A science class, the teacher asked the students to bring purple kale for the next class, as well as orange juice, Sprite, and some fruits. Everyone was puzzled: purple kale? What's the point? Is the next class going to be a cooking class? A moment everyone began to guess up, the teacher smiled and said: "Oh, don't guess wildly, the next class will reveal the answer!" The teacher said, "Don't guess anything, we'll find out next class!" The teacher was really kidding, it must be very interesting, I'm really looking forward to the next science class! Finally, we got to science class. We all brought kale and other items as required, and the teacher said, "We're going to do an experiment in this class, and we're going to do a magic show." The teacher broke off the leaves of the purple kale one by one, and then torn into tiny pieces, put into a cloth bag, and rubbed and squeezed with his hands vigorously, after a while, a drop of purple kale juice fell into the pre-prepared glass bottle, and then more than half of the bottle, the teacher looked at the glass bottle: "Oh, it's enough!"

The teacher took out a few beakers, which has been loaded with different 'liquids, Sprite, white wine, baking soda, etc., look like water, colorless, pure and transparent, small and large beakers filled with the entire podium, the teacher asked the question: "If the purple kale juice drops into these liquids, you think there will be what changes? " The students spoke out of turn to guess up, some say will change color, some say there is no change, some say that the purple will disappear, and some even said it will be the flavor of these liquids are gone ...... is really a variety of ah! The teacher smiled and said, "Let's just let the facts speak for themselves!" She put a long dropper into the purple kale juice, sucked a tube full of, and then dropped into the beaker respectively, eh, Sprite actually turned pink, baking soda water actually turned light blue ...... is really amazing, we rushed to record all of these.

The students have raised their hands to ask questions: " Teacher, why put the same purple kale juice drops in, these liquids will become different colors?" The teacher smiled and gave us the answer to the mystery: "Kale juice is a natural test agent, can measure the acidity or alkalinity of the items, because it will turn red when acid, alkali will turn blue or green." Oh, so it is, purple kale juice is really magical! It seems that the ordinary life also contains countless scientific wonders ah!