"Dolphin Bubble" is an app that helps children practice word spelling. In the app, the children spell the words on the bubble based on the bubbles spitting from the fish mouth. If the spelling is wrong, you need to correct it as soon as possible, and the bubble can be changed before it goes from the left side of the screen to the right. If you dont spell the word correctly before it reaches the far right of the screen, bubble will be punctured. If the word is spelled correctly, it will float out of the sea and get a score. One letter gets one point, and as the total score increases, the difficulty of the word will gradually increase.