Error-prone problem 1:
□-□=□-□=□-□= 1
Wrong example: 9-8= 1-8=7-6= 1.
Method guide:
Let the students know the meaning of "=" first, that is, regard □-□ as a whole and draw a horizontal line under it to show emphasis. All such integers are equal to 1. Then let the students think □-□ = 1. After the final completion, they can read to deepen their understanding of the whole -5-4 = 1, 3-2= 1 and so on.
Error-prone question 2:
□●○☆■△▲
(1) From the left, □ is the () th and () is the fifth.
(2)▲ is the first, ○ is the first (), and six is ().
Example of error:
(1) From the left, □ is the eighth, () is the fifth.
(2)▲ is the first, ○ is the third, and the sixth is (■).
Method guide:
(1) Remind students to count from left to right according to the first sentence, first find the left, then count from left to right, determine the position of the figure, and draw the figure in the corresponding position.
(2) Remind students to count from right to left according to the first sentence, first find the right, then count from left to right, determine the position of the figure, and draw the figure in the corresponding position.
Error-prone question 3:
In the queue, there are four people in front of Xiaohua, three people behind Xiaohua, and one * * * has () people.
Example of error:
When waiting in line, there are four people in front of Xiaohua, three people behind Xiaohua and one * * *(7) person.
Method guide:
This is a very familiar life scene. You can invite one student to be a flower, four in front and three in the back. How many parts can this team be divided into? Which parts? Students easily forget Xiaohua. Students can confirm that it can be divided into front of Xiaohua, behind Xiaohua and after Xiaohua. It is not difficult to list the continuous addition formula of 4+3+ 1, and it is concluded that * * * has 9 people.
Error-prone question 4:
There are three apples, five pears and eight bananas. Xiao Fang can choose two kinds of fruits. She can get at most () and at least ().
Example of error:
There are three apples, five pears and eight bananas. Xiao Fang can choose two kinds of fruits. She can get at most (16) and at least (3).
Method guide:
Let the students talk about which fruits are the most, which fruits are the least, which two fruits are more and which two fruits are less, and then emphasize that only two fruits can be selected. When thinking about these two questions, ask, "What kind of fruit don't you choose?" Ask students to give reasons, and guide them to tell which two kinds of fruits are more and which two kinds of fruits are less. Finally, it is concluded that to solve the problem of how much you can take is to choose more and two kinds of fruits, not the least, and to solve the problem of how much you can take is to choose less and two kinds of fruits, not the most.
Error-prone question 5:
Eight children played hide-and-seek, and two children have been caught, and () children have not been caught.
Example of error:
Eight children played hide-and-seek games, two children have been caught, and (6) children have not been caught.
Method guide:
First, let the students know the rules of the game. How many of the eight children are caught and how many are hidden? Then according to the two children who have been caught, we can merge the two children who have been hidden and remove the remaining five, so that five children are not caught.