1. LESSON PLAN
Level : Junior High School
Subject : Mathematics
Class : IX
Semester : I
Topic : Geometry and Measurement
Standard Competence : 1. Understanding the similarity
of figures and the use in problem
solving
Time Allocation : 2 x 40 minutes
Standard Competence
1. Understanding the similarity of figures and the use in problem solving
Basic Competence
1.2 Identifying the properties of two similar and congruent triangles
Indicators
1. Identifying two congruent or incongruent figures by showing the
requirements.
2. Determining two congruent triangles.
3. Determining the proportions of the sides of two congruent triangles.
4. Mentioning the properties of two congruent triangles.
5. Mentioning the requirements of two triangles to be congruent.
6. Proving two congruent triangles.
7. Distinguishing the concept of similarity from congruency.

2. Learning Objectives
1. Given the general definition of congruency, students can identify two
congruent or incongruent figures from the models provided by teacher
by showing the requirements.
2. Given several pair of triangles, students are able to determine whether
they are congruent or not.
3. Given two congruent triangles, students can determine the proportions
of the sides of the two triangle.
4. Students are able to mention the properties of two congruent triangles.
5. Students are able to mention the requirements of two triangles to be
congruent.
6. Given two triangles, students can prove that they are congruent.
7. After learning about similarity and congruency, students are supposed
to be able to distinguish the concept of similarity from congruency.
Learning Model
Learning Model : Conceptual Teaching
Learning Approach : Direct Presentation
Learning Method : Lecture Method, Question-Answer Method
Learning Sources
Handbook
Learning Materials
White board and board markers
PowerPoint Presentation

3. Learning Activities
 Apperception (± 10 minutes)
1. Phase 1. Clarify aims and establish set
o Teacher communicates the outlines of basic competence and
indicators that will be learnt.
o Teacher leads students to recall the lesson that had been learnt in
the previous meeting.
o Teacher prepares the material and sets students ready to learn.
 Main Activities (± 60 minutes)
2. Phase 2. Input examples and nonexamples
o Teacher names the concept being learnt and informs it to the
students. In this case, the concept is congruency.
o Teacher explains the general definition of congruency.
o Teacher provides students several figures and asks students
whether the figures are congruent or not.
o Further, teacher provides students several pairs of congruent
triangles and asks students to determine the proportions of the sides
of the triangles.
o Teacher leads students to mention the properties of two congruent
triangles.
o Teacher then poses the conditions in which two triangles are said to
be congruent.
o Students, by the guidance of the teacher, try to conclude and
mention the requirements in which two triangles are said to be
congruent.
o If it is possible, teacher can provide more examples and
noexamples of congruent triangles by leading the students to give
reason why the triangles are said to be congruent.
3. Phase 3. Test for attainment
o To check whether students have mastered the concept of
congruency or have not, teacher can ask several students randomly.
The questions can vary from determining whether two triangles are

4. congruent or not to rementioning the properties of two congruent
triangles and the requirements in which two triangles are said to be
congruent.
o Teacher then can give small quiz to the students to check their
understanding entirely. The questions in the quiz may vary from
proving that two triangles are congruent to providing their own
examples and nonexamples of two congruent triangles with the
reason/s.
4. Phase 4. Analyze student thinking processes and integration of
learning
o Teacher gets students to think about their own thinking processes,
about what they have learnt from that meeting. Teacher can modify
this activity by asking students to summarize what they have learnt
that day in a piece of paper without taking a look at the book or any
other sources. The only source of the summarization is student
understanding.
o Teacher then collects student summarizations and informs the
students that the score they get from the summarization will
contribute to their score of the quiz.
o Teacher then leads the students to integrate this new concept (about
congruency) by relating this concept to the previous concept which
is similarity.
o Teacher leads the students to again recall the concept of similarity
and then to compare the concept of similarity with the concept of
frequency.
o Teacher helps students to distinguish the concept of similarity from
the concept of congruency.
 Closure (± 10 minutes)
o Teacher leads students to conclude what they have learnt that day,
this can be modified by opening ‘question’ session.

5. o Teacher can also give homework to the students before closing the
lesson. The homework can be provided by the teacher or by the
book students have.
Assessment
The assessment can be done by assessing the quiz given. In assessing the
quiz, teacher should give feedback for each student.