https://drive.google.com/open?id=1IgmHjg1xhANpnxUBdLZskBJOx0ItgWyz&usp=drive_fs
x廷直接借由圖片協助認字 https://www.youtube.com/watch?v=XKSfquYBK0o&ab_channel=陳東甫 https://www.youtube.com/watch?v=cPGDkQpc37c&ab_channel=陳東甫
數學自製四則運算線上練習
https://aday0123.github.io/math/subtraction_final.html
https://aday0123.github.io/math/additionGame(mobile).html