2. Add and keep the carry.

Don't forget to bring 1 when calculating.

As shown in the figure:

In 1 and two-digit plus two-digit carry addition, the longitudinal calculation of two-digit plus two-digit carry addition is the focus of this lesson, and the problem of how to carry the digits to ten is the difficulty of teaching.

2. Because some children have been exposed to the vertical usage in previous studies, I asked students to list their own formulas when solving the problem of "how many fish are there in the fish tank on the left", and then asked students to ask questions about their own formulas, and finally led to "Why is one in ten?"

3. Although students have the basis of two-digit plus one-digit carry addition. But most students still don't know why they want to enter the tenth place. In order to further break through the difficulty of handling, I designed a link for students to calculate by themselves in teaching, so that students can realize the truth of entering the tenth place after they have reached the tenth place by putting a stick.

4. Then use courseware to show the beads that can't be dialed more than 10 on a number of the counter, so that students can understand the truth of full decimal into one more deeply. This will make the students more impressed. At this time, students will do corresponding joint exercises. Let students understand the importance of asking questions with critical eyes. Then use the octopus problem to consolidate children's calculations and achieve the goal of consolidating key points.

From the feedback, most children have mastered it, but some children have made mistakes carelessly. But what some children are wrong is not that they don't know arithmetic and calculation methods, but that they read the numbers and symbols wrong. It can be seen how careless and sloppy they are.