# Construction and Sketches

**FIRST TERM **

**SCHEME OF WORK WITH LESSON NOTES**

**Subject : **

**BASIC TECHNOLOGY**

**Topic:**

**Definition and Types of Triangles**

**Term :**

**FIRST TERM**

**Week:**

**WEEK 12**

**Class :**

**JSS 2 (BASIC 8)**

**Previous knowledge:**

**The learners have previous knowledge of **

# Rescue Operation

** that was taught as a topic during the last lesson **

.

**Behavioural objectives:**

By the end of the lesson, the pupils should be able to

- construct shapes
- construct angles

**Instructional Materials:**

- Wall charts
- Pictures
- Related Online Video
- Flash Cards

**Methods of Teaching:**

- Class Discussion
- Group Discussion
- Asking Questions
- Explanation
- Role Modelling
- Role Delegation

**Reference Materials:**

- Scheme of Work
- Online Information
- Textbooks
- Workbooks
- 9 Year Basic Education Curriculum
- Workbooks

**Content:**

**Outline:**

- Construction of Triangles

Construction of Triangles

**(A) To construct a triangle given the length of the three sides**

- Draw a horizontal line and mark off the base of the triangle AB.
- With centreA and a radius equal to the length of the side of the triangle, strike an arc.

iii. With centre B and a radius equal to the other side, strike another arc to cut the previous one at C.

- Join CA and CB to obtain the triangle ABC.

**(B) To construct a triangle given two sides and the included angle**

- Draw a horizontal line and mark off one of the given sides AB.
- At A, construct the given included angle BAC with the aid of a protractor.

iii. With centreA and a radius equal to the other given side of the triangle, cut AC at D.

- Join DB to complete the required triangle ABD.

**(C) To construct an equilateral triangle using compasses**

Note: An isosceles triangle may be similarly constructed once its base and sides are given. The equilateral triangle may also be drawn using the 600 set-square.

**(D) To construct an equilateral triangle using 600 set-square**

- Draw a horizontal line and mark off base AB equal to the given side.
- Slide the T-square below AB. Place the hypotenuse side of the 600 set-square on the t-square.

iii. Through A, draw AC at 600.

Reverse the set square, and through D draw BD at 600. AC and BD intersect at E to give the equilateral triangle EAB.

**ASSESSMENT**

- Construct an equilateral triangle using compasses.

** **

**Sub Topic: Geometric Construction – Angles (cont’d)**

**Content:**

**Bisection of angles****Construction of Angles**

**Bisection of Angles**

*To bisect a given angle*

- Draw a given angle ABC
- With centre B and any convenient radius draw ab arc to cut AB and D and BC at E.

iii. With centre A1 and any small radius draw an arc.

- With centre E and same radius draw an arc to intersect the previous one at F
- Join BD, BD bisects angle ABC, i.e angle ABD = and DBC
- Use a protactor to check angles ABF and CBF.

**Construction of Angles**

**Constructing a 90 Degree Angle**

- Draw a line with the measure is 5 cm 5 cm
- Draw point A at the line A

iii. Place the point of the compass at A and draw an arcthat passes through the line at point P and Q P A Q

- Place the point of the compass at P and draw an arc that passes through Q P A Q
- Place the point of the compass at Q and draw an arc that passes through P that cuts the arc drawn in Step 4at R. R P A Q
- By using ruler, joint A to R, so angle RAQ is 90 degree R 90 degree P A Q

**Constructing a 60 Degree angle**

- Draw the arm PQ. P Q
- Place the point of the compass at P and draw an arc that passes through Q. P Q

iii. Place the point of the compass at Q and draw an arc that passes through P. Let this arc cut the arc drawn in Step 2 at R. R P Q

- Join P to R. The angle QPR is 60 degree R 60 degree P Q

**Constructing a 30 degree Angle**

- Construct 60 degree angle R 60 degree P Q
- With the point of the compass at P, draw an arcintersecting arm PQ at M and intersecting arm PR at N. R N 60 degree P Q M

iii. At point M and N draw an arc with same radius thenintersect at point T R T N 60 degree P Q M

- Join P to T. Then angle TPQ is 30 degree R T N 60 degree 30 degree P Q M

**Constructing a 45 Degree angle**

- Construct 90 Degree angle R P Q
- Put your Compass at the point P, and draw an arc intersect PQ and PR at A and B. R B P A Q

Constructing a 45 Degree angle Step

iii. Put your Compass at the point A and B then draw an arcwith the same radius so intersect each other at the point C C R B P A Q

**Constructing a 45 Degree angle**

- Joint P to C, so angle CPQ is 450 C R B 45 Degree P A Q

**ASSESSMENT**

- Construct a 45 degree angle.
- Construct a 60 degree angle
- What are the steps taken to bisect an angle?

**Presentation**: The topic is presented step by step

Step 1:

The class teacher revises the previous topics

Step 2.

He introduces the new topic

Step 3:

The class teacher allows the pupils to give their own examples and he corrects them when the needs arise

**Evaluation:**

- Define Triangle?
- The sum of the three angles of any triangle is___

**Conclusion:**

The class teacher wraps up or concludes the lesson by giving out a short note to summarize the topic that he or she has just taught.

The class teacher also goes round to make sure that the notes are well copied or well written by the pupils.

He or she makes the necessary corrections when and where the needs arise.

** **