Teaching objectives

1. Let students know about measuring tools, such as benchmarking, tape measure and rope ruler.

2. Use tools such as tape measure and measuring rope to directly measure the short distance on the ground.

3. You can measure a straight line with the benchmark and measure a distance along the straight line.

Teaching focus

Use the tool measurement method.

Teaching difficulties

A method of determining a straight line.

Prepare teaching AIDS and learning tools

1. Three pillars, a tape measure (or rope) and several wooden stakes.

2. courseware? Measured? .

3. Print the linear measurement records.

Team leader (), team member ()

Teaching step

First, pave the way for pregnancy.

1. Measure the length and width of the blackboard with a meter ruler.

Note: Because the area of the blackboard is not too big, you can measure its length and width with a meter ruler.

2. If a rectangular playground with a length of150m and a width of100m is to be built, the workers' uncles will also measure the land section by section with a meter ruler. What do you think will happen?

Students answer: waste of time, inaccurate results, irregular shapes, etc.

Second, explore new knowledge.

1. Introduction. In industrial and agricultural production, it is necessary to survey land for building water conservancy, leveling land and building houses. The knowledge of surveying land is very useful for our future work. In this lesson, we will learn about the actual investigation.

2. Understand the measuring tools.

(1) post. It is used as a marker when measuring long distances. You can make it yourself. Usually, the surface of the column is painted with red and white every 10 cm to make it look obvious. Question: Why is one end of the column pointed? (easy to insert underground)

(2) Tape measure and measuring rope. A tool for measuring close range. The measuring rope can be made by yourself. Measurement is made in meters (decimeter is divided and marked in the first paragraph).

Question: What kind of rope is better for self-made rope measuring? Why? (small flexibility, easy to measure accurate data)

(3) Small red flag: used as a command signal during measurement.

3. Measure closer distances.

(1) Name two groups of students who measure the length and width of the classroom with tape measure or rope.

(2) Question: What problems should be paid attention to when measuring?

Through actual measurement and observation, guide students to draw the conclusion that the tape measure or rope should be straightened naturally during measurement, and the tape measure should not be stretched too tightly or too loosely to bend.

4. Measure long distances.

(1) Explain the significance and function of measuring straight lines.

When it is necessary to measure the distance between two distant objects, it is not enough to use only a tape measure and a measuring rope. It is necessary to measure a straight line between the distances to be measured first, and then measure the distance in sections along this straight line. Think about it, why?

Let the students know that if you don't measure the straight line first and then the distance, there may be twists and turns in the cross-section measurement, which will reduce the accuracy of the measurement results.

(2) Determination of straight lines.

Would you please read the courseware? Measured? Discuss with each other: How many steps are there to determine a straight line? To sum it up.

① Insert a datum at both ends of the measuring distance (point A and point B).

Blackboard writing: (1) Determine the starting point and the ending point.

(2) the first person in a command, ask the third person to insert roof of the world in point C, so that the pole at point B and it are blocked by the pole at point A at the same time, and the three poles are in the same line. The distance between the pole at point B and the pole at point C should be slightly shorter than the length of the tape or rope.

Pull out the post and nail the stake, numbered 1, starting from 0.

Writing on the blackboard: (2) Set the third benchmark.

(3) Similarly, insert the third pillar at point D, nail the pile and number it, so that the third pillar gradually approaches the second pillar, and the distance between them is shorter than the length of tape measure or rope.

Blackboard writing: (3) Repeated benchmarking.

④ Connect the point where the third datum point is inserted with point A and point B to determine a straight line.

Writing on the blackboard: (4) Connect the points into a straight line.

(3) After measuring the straight line, measure the distance between point A and point B with a tape measure or measuring rope.

(4) summary. Question: What should I do first when measuring a long distance? Do what again? How to determine a straight line?

(5) Outdoor operation: First, determine two points in the campus, insert a benchmark, measure a straight line through these two points, and then measure the distance between these two points with a tape measure or rope.

(1) announced the investigation team, designated team leader, clear requirements, put forward the appraisal conditions.

② Teachers lead the group to demonstrate. Combined with specific steps, pay attention to matters needing attention. For example, the datum must be upright. Let the students fill in the relevant data in the record form together with the cross-section measurement. ③ Each group measures straight lines and distances respectively. Teachers should pay attention to patrol guidance. ④ Summarize the evaluation.