Small animals in the car: 10 seat, nine small animals first, then five small animals, how to sit? Firstly, it is divided into 1+4, and students are interested, so the decomposition of 5 is naturally introduced.
With the help of intuitive model, the relationship between algorithms is handled. The key point is not to arrange in columns, but to use bitmap to help understand 12× 14, and turn this problem into learned knowledge, such as multiplying two digits by one digit. Multiply 14 by 12 and divide by 10 12 and 4 12 to show the arithmetic behind the formula. Then, connect the crack point diagram with four formulas of multiplication. Is it necessary to use an intuitive model for all computing classes? No. Combined with the specific teaching content, determine whether it is useful. Multiply three digits by two digits, and you can migrate. When adding and subtracting in primary schools, let the students edit their own questions to see who can make up new situations. A student's question is 3.4+2.86, which is exactly what this class will talk about. It undertakes the important task of aligning the same numbers and communicating the relationship between integer addition and subtraction and decimal addition and subtraction. Why is there no dislocation in the end? Do a good job in the teaching of counting units and guide all the operations of numbers.
About estimation: select the appropriate estimation unit and make estimation. It is important to pay attention to the order of magnitude, the power of 10.
Take estimation teaching as a whole and cultivate estimation consciousness as an important teaching goal. Create a situation: there are two numbers, three numbers, or an approximate range; Encourage diversification of methods, attach importance to the process of communication and explanation, and let students make reasonable estimates.