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Lesson Plan-Triangles (15.2)
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Measurable Annual Goal:
-Given a variety of two dimensional figures, the students will identify, classify,
compare, and find unknown angle measures with 90% accuracy.
Short Term Objective:
-When presented with pictures of various triangles (scalene, equilateral, isosceles,
right, acute, obtuse), the students will orally say what kind of triangle it is and
what angles/sides make it that kind of a triangle with 90% accuracy.
PA Academic Standard:
-M6.C.1.1.2: Identify and/or describe properties of all types of triangles (scalene,
equilateral, isosceles, right, acute, obtuse).
Materials:
-SMART Notebook Presentation
Procedures:
A. Introduction of Lesson
-Good morning boys and girls. Today we are going to be learning about the
different kinds of triangles. Does anyone have any ideas about what some of the
triangles we could be learning about are called? Call on various students to say
what some of the triangles are called. Provide immediate feedback for correct and
incorrect responses. The types of triangles are acute, right, obtuse, equilateral,
isosceles, and scalene. Today we are going to learn what makes a triangle an
acute, right, obtuse, equilateral, isosceles, or scalene triangle. Let’s get started!
B. Describe and model the skill or strategy
-There are six different types of triangles. On the SMART Board there are
pictures of the different triangles we are going to talk about. There are reasons
why these triangles are called their specific name. (Present the triangles in the
order that the slides on the SMART Notebook presentation occur.) Let’s look at
our first triangle and see why it is called an acute triangle. An acute triangle is a
triangle that contains only acute angles. An acute angle is an angle that is less
than 90 degrees (point to the acute angles in the acute triangle). All of these
angles are less than 90 degrees, which is why this triangle is an acute triangle.
Our next triangle is a right triangle. All right triangles have one right angle (point
to the right angle). Remember we know that a right angle is a 90 degree angle.
Our third triangle is an obtuse triangle. Obtuse triangles have one obtuse angle.
An obtuse angle is an angle that is greater than 90 degrees. The 110 degree
(point) angle in this triangle makes this triangle an obtuse triangle. The next three
triangles we are going to review are triangles that are classified by the lengths of
their sides. This triangle is an equilateral triangle. In an equilateral triangle all of
the sides are congruent. Remember congruent means “equal to one another”.
Each side in this triangle is 10 centimeters. An easy way to remember that an
equilateral triangle has all equal sides is that the word equilateral has the word
“equal” in it. Equal means the same and all of the sides in an equilateral triangle
are the same. This triangle is an isosceles triangle. Isosceles triangles are a little
different than equilateral triangles because they only have two sides that are
congruent (point to the two congruent sides). An easy way to remember if a
triangle is an isosceles triangle is that you have two eyes that are the same (point
to your eyes). Isosceles triangles have two sides that are the same. The last
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triangle we have seen is the scalene triangle. Scalene triangles do not have any
congruent sides. An easy way to remember if a triangle is scalene is that a fish
has many of scales. The scales on a fish are never the same because they are all
different. Scalene triangles do not have any sides of the same length.
C. Guided practice and interactive discourse
-Tell the whole class that you are going to look at a few triangles before playing a
game. Uncover the first triangle and point to it. Remind the students to look at the
lengths of the sides and angles in order to classify the triangle. After enough wait
time, tell the students to wait for your signal. The instructor will ask the next two
questions using the lead format (student and instructor answer together). The
signal should be visible and audible to the students. This is a (e.g. is a right
triangle). What triangle? (e.g. right triangle). A (e.g. right triangle has a 90 degree
angle). What angle does a right triangle have? (e.g. a 90 degree angle). All of the
students should answer in unison. If the students answer correctly, they will be
reinforced by a verbal reinforcer. If the students answer incorrectly, they will be
corrected immediately using the model-lead format (e.g. Teacher: This triangle is
a right triangle. What triangle? Student: A right triangle. Teacher: A right
triangle has a 90 degree angle. What kind of angle does a right triangle have?
Student: a 90 degree angle). The students will then start at the beginning of the
three triangle examples and continue with guided practice. Continue the unison
response with the students until you know all of the students are answering
correctly. Provide feedback every time.
D. Independent practice to mastery
-Go to the Identifying Triangles game on the SMART Notebook presentation.
Explain the instructions thoroughly to the students. Call each student
independently up to the SMART Board and have them drag one of the given
triangles into the appropriate classification area. If the student provides the
correct answer, give them positive feedback. If the student does not provide the
correct answer, model-lead-test the correct answer, and move on to the next
triangle (e.g. model-teacher instruction in part B, lead-teacher and student unison
response, and test-correction format shown in part C). The students will each get
a turn to do this. Record answers on the evaluation chart to decide if more reteaching is necessary.
E. Review /Feedback/ Closure
-Today we learned the different types of triangles and talked about why each
triangle is classified as that type of triangle. We talked about angles and sides and
why it is important to look at them in order to properly classify triangles. Give
feedback to the students on how well they did in today’s lesson.
Evaluation:
-The instructor will informally assess the students throughout the lesson. The
instructor will assess the students on their ability to correctly drag specific
triangles into the correct classification box. This evaluation will be used to decide
if reteaching triangles is necessary.
Critique:
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