My lesson plan is about teaching students how to calculate
the area of a triangle. I believe
that I could complete the lesson within two days but we may need a third day to
really understand all of the concepts.
The first day consists of reviewing how to find the area of a rectangle.
I would start by putting a few examples on the smart board and asking for
student participation. They should
already have an understanding of how to calculate the area of a rectangle but
if they have forgotten anything it is always important to have a quick review.
We start with calculating length multiplied by width, which hopefully the
students themselves will be able to explain. I will show students that this is the same as saying base
times the height. It will now be
easier to explain to the students how to get the formula for area of a
triangle. I will start the
explanation by drawing another rectangle on the smart board and drawing a
diagonal line across the center. if By drawing this diagonal line across the
rectangle the students will be able to see that we would get two
triangles. I will ask the students
to use their critical thinking skills to see if they can tell me what area of
one of the triangles is given the area of the whole rectangle. Hopefully
through this visualization the students will be able to tell me that to find
the area of one of those triangles we would simply divide the number we have
for the rectangle by two. This now gives us the formula one half times base
times height. At first it is
easier to work with only right triangles because they are easier to draw and
measure. When using right
triangles the students can draw two equal triangles and make a rectangle, which
also helps them better understand the formula we just came up with. After allowing the students to explore
these concepts and formulas using graph paper, pencils, rulers and protractors,
we will discuss acute and obtuse triangles. The students must first understand the difference between
these two triangles and how to draw them.
After practicing drawing these two new types of triangles, I will
explain to the students that the same formula we used for finding the area of a
right triangle also works for finding the area of an obtuse or acute triangle. The only difficult part about this of
course is finding the height of the triangle. I will of course have to explain that the height or altitude
of a triangle is the line segment from one vertex (or angle) of a triangle to
the opposite side so that the line segment is perpendicular (or forms right
angle) to the side. The students
will work in groups to draw and label the sides and heights of different
triangles. Using The Geometer
Sketchpad the students will have to create three examples of each different
type of triangle (right, obtuse and acute). The students will then record the data (lengths of sides and
altitude) that they themselves have created on the computer and use that data
to calculate the area of each triangle.
In this activity the geometer’s sketchpad is extremely useful because it
will allow the students to explore many different types of triangles as well as
better understand the relationship between base and altitude and the opposite
vertex. On top of all this, it
gives the students accurate measurements of angles and sides so that they can
have more accurate data and more accurately calculate the areas of their
created triangles. The final
assignment of the lesson will to be to calculate the area of different shapes
that I give them using their new information about triangles. I will give the students a few
different shapes such as octagons and stars, which they will have to break up
into different size and shaped triangles in order to find their areas. The students will use the geometer’s
sketchpad to draw the triangles inside the given shapes. They will then label
the measurements for each side and calculate the area of each small triangle
that they have created. Adding the
areas of the triangles together they will be able to calculate the area of each
of the given shapes. They will
have to submit their work and drawings online as well as show how they calculated
each area on paper so I can feel confident that they have understood the
lesson.
The following is the link to my lesson plans:
https://docs.google.com/spreadsheet/ccc?key=0AoktAYMszf1ndENsSDF0YzVBUFdnSVFwUU16M250Mmc
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