LESSON PLANLevel : Junior High SchoolSubject : MathematicsClass : IXSemester : ITopic : Similarity and CongruenceStandard Competence : Understanding the similarity offigures and the use of it in problemsolvingTime Allocation : 2 x 40 minutesStandard CompetenceUnderstanding the similarity of figures and the use of it in problem solvingBasic CompetenceUsing the concept of similarity of triangle in problem solvingIndicators1. Determine the ratio of the side of two triangle that are similar and calculate itslength2. Solve problem related with similarity of a triangleLearning Objectives1. Students are able to determine the ratio of the side of two triangle that are similarand calculate its length2. Students are able to solve problem related with similarity of a triangleLearning ModelLearning Model : Class DiscussionLearning Approach : Direct Presentation
Learning Method : Lecture Method, Question-Answer MethodLearning SourcesHandbookLearning MaterialsWhite board and board markersPowerPoint PresentationLearning Activities Apperception (± 10 minutes)1. Phase 1. Clarify aims and establish seta. Teacher communicates the outlines of basic competence andindicators that will be learnt.b. Teacher leads students to recall the lesson that had been learnt in theprevious meeting.c. Teacher prepares the material and sets students ready to learn. Main Activities (± 60 minutes)1. Phase 2. Focus the discussiona. Teacher divides the students into several groups that contains of 2-3students in each group.b. Teacher extends problems that will be discussed (as a worksheet).c. Teacher gives time to students to solve the problem and discusswith their group.2. Phase 3. Hold the discussiona. After all the students solve the problems, teacher starts the discussion.b. Teacher asks 1 group to present their idea to the whole class bywriting the answer on the whiteboard.c. The teacher asks the other group to give their opinion about theirfriend’s answer by raising their hand.
ab24 3088415d. In the middle of the discussion, teacher may also present his/her ownideas to the class to keep the discussion alive.3. Phase 4. End the discussiona. Teacher gives feedback about the student’s answer.b. After doing the discussion, students summarize the material that havebeen discussed.4. Phase 5. Debrief the discussiona. Teacher asks students to examine their discussion and thinkingprocesses. Closure (± 10 minutes)a. Teacher leads students to conclude what they have learned that day.b. Teacher may also give homework for students to practice.c. Teacher closes the lesson that day.AssessmentIndividual Assessment : ParticipationGrouped Assessment : Worksheet, participation1. Calculate the length of a and b.2. State, with reasons, whether ΔABC is similar to ΔPQR and find the value of x.
3. The figure shows two similar cones.a. Find the value of x.b. What is the ratio of the base circumference of the smaller cone to that of the bigcone?4. A model of an apartment block is made to a scale of 1 : 50.a. Find the actual height of the apartment block if its height on the model is 42cm.b. If the area of the hall of the apartment is 34 m², find the area of the hall on themodel.c. If the area of a unit of the apartment is 1200 cm² on the model, find its actualarea in m².