# Lesson Notes By Weeks and Term - Senior Secondary 1

Special curves I

TERM – 3RD TERM

WEEK ONE

Class: Senior Secondary School 1

Age: 15 years

Duration: 40 minutes of 5 periods each

Date:

Subject: Technical Drawing

Topic: SPECIAL CURVES I

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

I.) Describe special curves.

II.) Construct an eclipse.

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures,

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

 PRESENTATION TEACHER’S ACTIVITY STUDENT’S ACTIVITY STEP 1 INTRODUCTION The teacher identifies and describes special curves. Students listens attentively to the teacher STEP 2 EXPLANATION Teacher guide students to construct special curves, e.g. eclipse Students exhibit attentiveness and active engagement STEP 3 NOTE TAKING The teacher writes a summarized note on the board The students copy the note in their books

NOTE

SPECIAL CURVES I

Loci refers to the set of all points that satisfy a given condition or set of conditions. It is a fundamental concept in geometry and is often used to describe the paths or shapes formed by points that meet specific criteria.

Ellipse.

An ellipse is a closed curve that resembles a flattened circle. It is defined as the locus of all points in a plane such that the sum of the distances from two fixed points (the foci) is constant. Ellipses have several properties, including major and minor axes, eccentricity, and focal points.

Applications of Ellipses

1. Ellipses describe the orbits of planets, comets, and other celestial bodies around the sun or other celestial objects.
2. Ellipses are used in the design of mechanical components, such as gears, bearings, and cams.
3. Elliptical mirrors and lenses are used in optical instruments like telescopes and cameras.
4. Elliptical shapes are employed in architectural design for structures like arches, windows, and domes.

Construction of Ellipse

1. Prepare the length the major axis (longest diameter of an ellipse)

2. Draw one horizontal line of major axis length.

3. Mark the mid-point with a ruler by taking the length of the major axis and dividing it by two.

4. Draw a circle of this diameter with a compass.

5. Decide what length the minor axis (shortest diameter of an ellipse)

6. Draw another line bisecting the major axis (which will be the minor axis) using a protractor at 90 degrees.

7. Draw a circle of this diameter with a compass.

8. Divide the entire circle into twelve 30 degree parts using a compass.

9. Draw horizontal lines from the inner circle (except on major and minor axis).

10. Draw vertical lines from the outer circle (except on major and minor axis)

11. Darken all intersecting points including the two ends on the major (horizontal) and minor (vertical) axis.

12. Join the points using free-hand drawing or a French curve tool (more accurate)

EVALUATION: 1. An eclipse has a major axis 120 long and its foci are 80 apart.

I.) Construct the eclipse

II.) Measure and state the length of the minor axis. (WAEC)

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively