Trapezoidal area of instructional design

 Instructional design

teaching objectives:

1. in practical situations, recognizing the need for calculation of trapezium area.

2. in self-exploration activities, the trapezoid area formula is derived through the process.

3. Trapezoid area can use the formula to solve the corresponding practical problems.

teaching focus: to understand and grasp the trapezoid area formula.

teaching difficult: to understand trapezoid area formula derivation.

preparing teaching aids: Two copies each of a variety of ladder, scissors, courseware.

teaching process:

First, creation of scenarios, revealing issues.

1, recently, naughty family car has a problem, we look at what problems he encountered? (Click courseware)

he wanted to change a new glass, you can help him solve this problem?

then we should consider what factors?

Now we take a look at what this windscreen shape? How do you know a ladder?

we determine its shape is trapezoidal, the want to know how much to buy, we should know that this wind

glass area. This lesson we will explore together and naughty trapezoid area, to help him solve the problem.

2, writing on the blackboard issue: trapezoid area (blackboard)

two organizations to explore, acquire new knowledge.

1, review the derivation of the triangle area formula.

2, in order to know the area of the triangle, we must first know the end of the triangle, and high. if I tell you on the ladder's end and high end of the length of the next is not also under these conditions, obtained the area of trapezoid?

then we intend to how to do it?

groups around the

① how to ladder into the graphics we have learned?

a good discussion of the group before the method to be used, a team with a pair of scissors can cut and complement, to determine what should be converted into graphics?

② look into the bottom after the graphics and high-end and high with the trapezoid What is the relationship?

③ how to derive the formula for calculating the trapezoidal area?

a variety of teacher preparation to the various groups of the two and a pair of scissors ladder.

3. student operation, group discussions with each other, teachers patrol.

4. According to the discussions, reporting.

① invited representatives of the first group to report first to the top.

teacher with a computer presentation of their ideas again and which is again followed by the students?

② It is this group's discussions, what other groups with different ideas? Please come to report on behalf of this group.

③ what other groups with different ideas? Please come to report on behalf of this group.

Now we follow this approach the triangle area formula of presentation again: two identical trapezoidal ... ...

(presentation side edge derived) trapezoid area = (base + down on the bottom) × high ÷ 2 (after the s begin writing on the blackboard)

5. letter formula.

(click courseware) If you use a ladder that's on the bottom, b that the end of the next ladder, h said the high ladder, S said that the area of trapezoid, then the trapezoid area formula for how to use the letter that it can be ?

S = (a + b) h ÷ 2 (Blackboard)

Third, the application

1,UGG boots, now we can use the trapezoid area formula to help solve the problem naughty. After measuring, I already know the front windshield of the car end and high end of the length of the next, see. (Click courseware)

formula you use the glass to help him figure out the area of trapezoid? Calculated according to what is it?

(because we have only just learned trapezoid area formula, it is best to write out the formula and then calculated. Note that to use a unit of area.)

2. There is a dam, it is trapezoidal cross-section, you Dangdang small engineer, calculate the area of trapezoid cross-section of the dam. (Click courseware)

what basis do you calculate it?

3, a pile of steel pipe pile, and naughty want to know the number of pipe, you can help him solve the problem?

(students solve , and organize students to understand the convenience of trapezoid area formula.)