崇仁1、组合图形的面积 - 光泽县崇仁新华中心小学-网站首页（1, the area of the combination of graphics - sheen County Chongren Xinhua Central Primary School - home page）

1、组合图形的面积-光泽县崇仁新华中心小学-网站首页1, thearea of the combination of graphics - sheen County Chongren

Xinhua Central Primary School - home page

First, review the introduction, reveal the subject

1, review the last lesson, characteristics about thecombination of graphics, method for the combination of graphicsarea.

2. Reveal the content of this lesson and write the topic onblackboard.

Two. Guiding practice

1 and first questions

(1) the students' independent thinking, segmented learnedarbitrary graphics.

A, B, display the student independent segmentationsegmentation

(2) students will be divided into graphic please least learnedgraphics.

(3) add the condition for segmentation.

A, students according to the conditions of B, why do this?2 and second questions

(1) free reading problems, understand it.

(2) formulation calculation

A, ask for the area of the wall to be painted first

10 x 1.6 / 2 x 410

B, and then figure out how many kilos of paint it will take

0. 15 X 48 = 7.2 (kg)

When communicating, if the students make a comprehensiveformula to calculate, as long as reasonable, teachers shouldalso be affirmed.

3 and third questions

(1) read the question freely and discuss how to solve theproblem of "how much paint is needed. ".

(2) students practice

(3) reporting feedback.

Three. Exercise independently

(1) presentation exercises

1. narrative calculation thinking.

The students discuss with each other exchange.

2. for the upper icon on the data, the area.

Can the students finish after the exchange.

3. narrative calculation thinking.

S umm ary:

First, the combination graph is divided into several basicplane figures, and the area is calculated by the basic figurearea formula, and then the parts are added together.

(two) solving problems

There is a irregular, figure, if the area of

0.2 square meters of floor tiles, at least the number of tiles?Four. Summary of the whole lesson

Through this class of practice, what was your experience?Five, assignments: seventy-fifth pages of practical activities2, exploration activities - "footprints of growth"

Teaching contents: bjnu edition textbook of mathematics ninthpage 77-78 content.

Teaching objective:

1, knowledge and skills: can correctly estimate the size ofirregular graphics area, can use the number square method tocalculate the area of some irregular graphics, master the orderand method of the number grid.

2, the process and methods: by means of grid map estimation ofirregular graphics area, in the process of estimating the areaof experience to solve diversity strategy, develop preliminaryestimate consciousness and estimate the habit, experience thenecessity and importance of estimation.

3, emotion, attitude and values: understand the closerelationship between mathematics and real life, and feel theapplication value of mathematics.

Teaching emphasis: map estimation irregular figure area usinggrid.

Teaching difficulties: habits and the choice of estimationmethods.

Teaching thought:

In real life, the students will be exposed to the problem areaof a large number of irregular graphics, according to therequirements of the standard, let the students grasp theestimation of irregular graphics area, is one of the studentsthe concept of space, but also improve a student' s ability to

solve the actual problem. This class is the teachingmethod forstudents can master solving math problems and the.

Teaching preparation: a plurality of leaves, square piece ofpaper, a small blackboard says "do you know".

Teaching process:

A situation, guide, reveal new knowledge.

Today, the teacher brought two significant footprints. (thefirst footprints on the moon) . Maybe one day after several years,the first Chinese footprints on the moon are among the peoplepresent. Look at the second step: (show?Her footprints) thisis a millennium Baby Footprints pictures, how can we know howmuch this footprint area?

Two, participate in exploration, experience new knowledge1, his first independent estimates, then the exchange withinthe group.

2, the whole class exchange:

(1) explain the result and process of estimation

(2) the number square method is used to verify the estimatedvalue

(3) teacher: everyone is estimated by the method of the numberof squares,

Is there any other estimation method?

Guide the students to look at the graphics as approximategraphics, and calculate the area according to the area formulaof the graph

3, show the two Xiaohua footprints, students estimated area:Three, summary method, practice new knowledge:

(1) teacher: just nowyou estimate the area of irregular figuressuch as footprints. Think about what methods you used toestimate

Divisionwriting: 1. With the help of the grid map count number.2, take it as an approximation of the regular figure, aftermeasuring calculation.

(2) ask the students to count their footprints of the area isabout how much?

The students take their first independent step, and with thehelp of the attached 3 grid footprint area estimation.Four, new knowledge practice, solve the problem:

1, to estimate the irregular Seventy-eighth page graphics area:(in order to produce courseware)

(1) students estimate independently:

(2) on the exchange students talk about how to estimate the.

2. Estimate the area of the palm:

(1) : each value your palm area:

(2) estimate and verify the students cooperation on the gridpaper: (this link tohelppoor students to carry out activities)

(3) report shows: (Teacher: we know that square decimeter, palmarea is about 1 square decimeter)

Six, classroom review, summary and improve:

Boys and girls, what do you have today?What do you have? Tellme。

Blackboard writing design:

Footprints of growth

Estimation of irregular figure area:

1, with the grid count.

2, take it as an approximation of the regular figure, aftermeasuring calculation.

Second class: area of practice -- estimation of leaves

Teaching contents: bjnu edition textbook of mathematics ninthvolume seventy-ninth pages.

Teaching process:

(1) revealing the contents of activities

(two) activity process

1. Select leaves

2. Estimate the area of a leaf:

(1) Division: each group took out the leaves, first calculatethe area of each other. Can direct to find its size by numberof squares?

(2) students discuss, named answer:

(3) birth report: (a) count on the grid. (b) the outline drawnon the grid paper, count.

(4) with each other about the results, see who the most accurateestimate.

3, understand the importance of green trees to environmentalprotection:

(1) if a tree with 10000 leaves, the total area of the treeleaves all estimate.

(2) in sunny days, about 25 m2 of leaves can release enoughoxygen for one person to breathe in one day. The tree in thesun, a day to release oxygen to meet the needs of many peopleto breathe?

Note: (show, do you know?)

You know what?

A person to live, need every day in 0.8 kg of oxygen, 0.9kilograms of carbon dioxide discharge. The 10 thousand squaremeters of forest oxygen can supply one thousand peoplebreathing.

Data introduction:

10 square meters of forest or 25 square meters of grass canabsorb all the carbon dioxide exhaled by one person every dayand supply the needed oxygen. Globally speaking, green forestevery year for people of nearly one hundred billion tons ofcarbon dioxide, 60%oxygen for clean air. The existing forest,the annual production of up to 55 billion 500 million kg ofoxygen.

4, talk about the feelings of this lesson.

Try and guess

The first class: Chicken with rabbit cage