Take out a new deck of playing cards, and the dealer will carefully wash the playing cards first, so that all the playing cards will bloom, so that there are no rules to follow. Then give it to several or several people to watch the memory and start the watch in time. They are not allowed to ventilate each other. Finally, give those people or people a deck of playing cards, and let them rearrange the remembered playing cards according to their memory to see who put the playing cards. Whoever plays cards in the same order as the original mother, whoever has the most cards will win.
Reflections on the teaching of fractional addition and subtraction 1
? The addition and subtraction of fracti