moving target

"How Big Is 100 Million" is a comprehensive activity practice class after learning the Understanding of Large Numbers, the first volume of the fourth grade of People's Education Press. Students feel the size of 1 100 million, and develop their sense of numbers through activities such as guessing, experimenting and asking questions. And let students experience and understand the research method of "calculating the whole from the part" in the inquiry activities. In the process of practical activities, we can accumulate the experience of mathematical activities, experience the happiness of cooperation and communication with others, and enhance our interest and consciousness in exploring mathematics.

Activity flow

1. Determine the research content:

Discuss in groups to determine the content and materials of study.

[design intent]? In order to stimulate students' interest in learning and their autonomy in learning, students can choose research materials and determine research contents according to their own preferences. In this process, students will also think about the rationality and operability of the research materials and make effective choices.

2. Think about the research plan:

Communicate the research plan in the group, including the tasks and division of labor of each member, the name of the activity, and report it. (See Figure 1 for division of labor and cooperation within the group)

[design intent]? Students' discussion is conducted in groups, and each child is made clear about his or her task through the form of table records. It is a process of concretizing and refining big tasks, which can cultivate children's good habit of planning and considering problems comprehensively at the forefront of activities. The process of reporting is also the process of students' clear division of labor.

3. Carry out the experimental operation:

Students complete the experimental operation in class, record activities, draw conclusions and prepare reports. (see figure 1)

[design intent]? By recording the activity steps, students can think while operating and sort out the order of doing things. At the same time, it can enhance students' cooperation ability and observation ability, and the students who record will carefully observe the students who operate and then record them accurately and in detail.

4. Group report exchange, class evaluation.

The whole class reports and communicates in groups, and other groups are judges.

[design intent]? Cultivate students' language expression ability, listening ability and evaluation ability. By observing and listening to the reports of other groups, we can also reflect on whether the methods in our activities are appropriate. Recognize the good things of others through comparative evaluation.

(2) Description of the scene

Scenario 1: Subject Report

Life-to-life dialogue and mutual questions

Students report to the class in groups. Students listen carefully and ask questions.

Health 1: We need to study how high 100 million coins stack up.

Health 2: What's the denomination of your coin? Are these 100 million coins the same coin?

Health 1: We are studying one-dollar silver coins.

Health 2: I have questions about folding. How do you fold it?

Sheng 1: Demonstration superposition. (The difference is that they are connected, and some groups study how long they are connected. )

For students, free choice of content is more autonomous and challenging. In the report of the first research topic and scheme, there are many dialogues among students, and students dare to constantly question and ask questions. In this process, students' questions are more quality and targeted. So as to exercise the rigor of students' expression and consider the comprehensiveness of the problem.

Scenario 2: Teamwork:

Everyone participates, and the division of labor is coordinated.

How thick is a group studying 100 million books? "(See Figure 3) During the experiment, when students measure the thickness of 1 this math book, 1 people put the book horizontally and vertically on the table for a while, and constantly adjust the appropriate measurement method. 1 person presses both ends of the book hard, 1 person measures, 1 person records and two people (accurate measurement). "

Figure 3 Measuring the thickness of a math book

Everyone participates in group cooperation, because in the report, the team leader must first evaluate the team members. Therefore, every child is actively involved and involved, and the team leader will also do a good job in organization and coordination. Some team members have strong calculation ability and high accuracy, so they arrange calculation work, while others arrange him to measure carefully.

In the actual operation process, it embodies the students' rigorous and focused scientific attitude and tacit and orderly teamwork. When evaluating team members, team leaders can also be fair and just, attach importance to each partner, have division of labor and cooperation, and give full play to the advantages of each team member.

(C) Teaching Enlightenment

1. Let students go through a complete problem-solving process.

The integrity of "problem-solving process" lies in that students can independently ask questions, clarify problems, solve problems and sum up ideas, accumulate more problem-solving experience and form similar problem-solving strategies. (test one first, and then draw a conclusion through calculation. )

2. Let students experience a complete team work process.

The integrity of the "team cooperation process" is reflected in the determination of team consultation and discussion in the theme, the clear voting in the problem, the division of labor and cooperation in solving the problem, and the report and collective display in the communication. Let students experience the fun of learning and communicating with each other in the process of cooperation.

3. Give students more time and space to explore.

The activity process is designed in the form of task list to stimulate students' desire for exploration. A week's preparation time ensures that students have more exploration space, so that students can truly show their performance and constantly adjust and improve themselves. Students can fully experience the process of problem solving and gain rich experience in activities.

4. The activity process design teachers should do a good job of moderate guidance.

At the beginning of the activity, the teacher should guide the students to do it clearly.

For example, "How big is 100 million? Activity start design:

"What problem do you want us to solve? What experimental preparations should be made? Do you really want to prepare 100 million pieces of paper? "

In the process of activities, teachers should participate in the process of group cooperation, give targeted guidance according to the problem solving situation of each group, and clarify how to do it.

In the activity summary, teachers should guide students to reflect on the problem-solving process and refine the problem-solving strategies.

(4) Evaluation description

Evaluation methods and tools

1, recorded in form, and evaluated by team leader and team members at the same time.

2. Report the classmates, teachers and classmates in the communication process, and evaluate them in time.

Evaluation design is more diverse: evaluation is to better promote development. Students' various performances in the process of "comprehensive practice" activities, how to feed back detailed evaluation information to students, through research, we adopt diversified evaluation methods and diversified evaluation subjects to evaluate students' performances in activities more comprehensively and flexibly.