Lesson Notes By Weeks and Term v3 - Primary 2
Two dimensional shapes.
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Two dimensional shapes.
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Subject: General Mathematics
Class: Primary 2
Term: 1st Term
Week: 11
Theme: Mensuration And Geometry
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Watch on YouTubeidentify a square, a rectangle, a circle and a triangle; in dicate which corner of a 2-dimensional shape is a “square corner”.
This section provides in-depth explanations of the core concepts related to two-dimensional shapes, specifically focusing on squares, rectangles, circles, triangles, and the concept of a "square corner." 2.
1. Two-Dimensional (2D) Shapes 2D shapes are flat figures that have only two dimensions: length and width. They do not have thickness. They can be drawn on a piece of paper or observed as the faces of three-dimensional objects. These are also known as plane shapes. 2.
2. The Square Definition: A square is a 2D shape with four straight sides that are all equal in length. It also has four corners.
Properties: It has 4 sides. All 4 sides are of equal length. It has 4 corners. All 4 corners are "square corners" (right angles).
Examples in Nigerian Context: The face of a dice, a checkerboard square, some floor tiles, a section of a "keke napep" side mirror, a typical picture frame, a small "gala" snack package face, some traditional Yoruba adire patterns. 2.
3. The Rectangle Definition: A rectangle is a 2D shape with four straight sides and four corners. Its opposite sides are equal in length.
Properties: It has 4 sides. Opposite sides are equal in length (the two longer sides are equal, and the two shorter sides are equal). It has 4 corners. All 4 corners are "square corners" (right angles).
Examples in Nigerian Context: A blackboard, a door, a window, the cover of a textbook, a mobile phone screen, a typical building brick face, a rectangular serving tray, a "dodo" (fried plantain) slice, the face of a matchbox. 2.
4. The Circle Definition: A circle is a round 2D shape that has no straight sides and no corners. All points on the edge of a circle are the same distance from its centre.
Properties: It has no straight sides. It has no corners. It is completely round.
Examples in Nigerian Context: A plate, a clock face, a car tire, a coin (e.g., ₦1 or ₦2 coin), the base of a water drum, the opening of a bucket, a "puff-puff" (doughnut) or "akara" (bean cake). 2.
5. The Triangle Definition: A triangle is a 2D shape with three straight sides and three corners.
Properties: It has 3 sides. It has 3 corners. The sides can be of equal or different lengths. It can have different types of corners, including a "square corner" (in the case of a right-angled triangle).
Examples in Nigerian Context: A slice of pizza or "puff-puff," the gable end of some traditional house roofs, a small kite, a section of a road warning sign (e.g., 'give way' sign), a piece of broken glass. 2.
6. Identifying a "Square Corner" Definition: A "square corner" is another name for a right angle, which measures exactly 90 degrees. When two straight lines meet and form a perfect 'L' shape, they create a square corner.
Identification Method:
1. Visual Inspection: Look for corners that look like the corner of a square or a rectangle.
2. Using a Reference Tool: Students can use the corner of a piece of paper (like an exercise book page or a ruler) as a reference. If the corner of the paper perfectly fits into the corner of the shape being examined, then it is a square corner.
Application to Shapes: Square: All four corners of a square are square corners.
Rectangle: All four corners of a rectangle are square corners.
Circle: A circle has no corners, therefore no square corners.
Triangle: Some triangles (called right-angled triangles) have one square corner. Not all triangles have square corners.
Examples in Nigerian Context: The corners of a door frame, window frame, blackboard, textbook, the edge of a wall where two walls meet at 90 degrees. Worked Example for Square Corner Identification: Scenario: A teacher presents a cut-out paper square, rectangle, and two different triangles (one with a right angle, one without). * Procedure:
1. The teacher takes a piece of paper (e.g., a sheet from an exercise book). The no square corners.
Triangle: Some triangles (called right-angled triangles) have one square corner. Not all triangles have square corners.
Examples in Nigerian Context: The corners of a door frame, window frame, blackboard, textbook, the edge of a wall where two walls meet at 90 degrees. Worked Example for Square Corner Identification: Scenario: A teacher presents a cut-out paper square, rectangle, and two different triangles (one with a right angle, one without).
Procedure:
1. The teacher takes a piece of paper (e.g., a sheet from an exercise book). The corner of this paper naturally forms a square corner.
2. Place the corner of the paper precisely over each corner of the square cut-out. Observe how the paper corner perfectly aligns with each corner of the square.
Conclusion: All corners of the square are square corners.
3. Repeat for the rectangle cut-out. Observe perfect alignment.
Conclusion: All corners of the rectangle are square corners.
4. Repeat for the right-angled triangle cut-out. Find the corner that perfectly aligns with the paper corner.
Conclusion: This specific triangle has one square corner.
5. Repeat for the other triangle (e.g., an equilateral or acute triangle). Observe that none of its corners perfectly align with the paper corner.
Conclusion: This triangle does not have a square corner. This practical demonstration helps students understand the physical characteristic of a square corner, rather than just a theoretical definition. This section outlines the step-by-step activities for the teacher and learners to achieve the lesson objectives. 3.
1. Introduction (10 minutes)
Teacher Activity: Begins by asking learners to identify shapes they see in the classroom (e.g., door, window, clock, table top). Holds up various real-life objects (e.g., a textbook, a plate, a piece of art with triangular patterns, a small square biscuit pack) and asks learners to describe their overall shape.
Student Activity: Learners volunteer to name observed shapes and objects. They describe what they see in terms of 'round,' 'straight edges,' 'pointy parts.' 3.
2. Development: Exploring Shapes (25 minutes)
Activity 1: Identifying and Naming Shapes Teacher Activity: Displays large flashcards or cut-out shapes (square, rectangle, circle, triangle). Presents each shape individually, clearly stating its name and key features (number of sides, number of corners). Draws each shape on the blackboard, labelling them.
Asks guiding questions: "How many sides does this shape have?" "Are the sides straight or curved?" "How many corners can you count?" "Are all the sides equal?" Relates each shape to familiar Nigerian objects.
Student Activity: Learners listen attentively, repeat the names of the shapes. They count sides and corners as the teacher points them out. They identify real-life objects in the classroom or from their daily lives that resemble each shape. Learners practice drawing the shapes in the air or on their desks using their fingers.
Activity 2: Identifying "Square Corners" Teacher Activity: Introduces the concept of a "square corner." Uses a real-life square object (e.g., a square ruler, a small square tile) or a cut-out paper square. Demonstrates how to use the corner of an exercise book or a piece of paper to check if a corner is a "square corner." Points to corners of a classroom door, window, or blackboard and asks learners if they are square corners, demonstrating with the paper. Draws a square, a rectangle, a right-angled triangle, and a circle on the board. Asks learners to identify which shapes have square corners and points them out.
Student Activity: Learners observe the demonstration. They use the corners of their exercise books or rulers to check for square corners on their desks, books, and other objects. They identify square corners on the shapes drawn on the board. Learners discuss their findings with a partner. 3.
3. Application and Practice (15 minutes)
Teacher Activity: Distributes worksheets or asks learners to open their exercise books. Provides specific instructions for drawing shapes and identifying objects. Organises a quick "shape hunt" in the classroom.
Student Activity: Learners draw a square, a rectangle, a circle, and a triangle in their exercise books. They point to objects in the classroom and identify their basic 2D shape (e.g., "The wall calendar is a rectangle," "The fan blades make a circle when it spins"). Learners identify square corners on their drawn shapes where applicable. 3.
4. Conclusion (5 minutes)
Teacher Activity: Reviews the names of the four shapes covered and their key characteristics. Emphasises the concept of a "square corner." Summarises the importance of knowing shapes in their daily lives.
Student Activity: Learners answer questions to recap the lesson, naming shapes and identifying square corners on demand. The teacher should guide students through these questions, providing support and clarifications as needed.
Question 1: Look at the pictures below. Name the 2D shape each object's face represents. a) A common wooden door b) A car tyre c) A slice of watermelon cut like a pie d) The face of a building block (like a cement block)
Solution 1: a) Rectangle b) Circle c) Triangle d) Rectangle (or Square, depending on the specific block, but rectangle is more common for typical building blocks)
Commentary: This question assesses the learners' ability to identify common 2D shapes in familiar objects, linking abstract shapes to real-world context.
Question 2: Draw the following shapes in your exercise book: a)
A square b)
A triangle Solution 2: a) [Teacher should draw a square on the board with 4 equal sides and 4 square corners.] b) [Teacher should draw a triangle on the board with 3 sides and 3 corners. A simple equilateral or isosceles triangle is sufficient for Primary 2.]
Commentary: This evaluates their ability to reproduce the shapes visually, demonstrating an understanding of their basic form. The teacher should observe for correct number of sides and corners.
Question 3: Look at these shapes: [Teacher draws a square, a circle, a rectangle, and a triangle (one with a right angle)] Which of these shapes has all its corners as "square corners"? Which of these shapes has no corners at all?
Solution 3: Shapes with all "square corners": Square and Rectangle.
Shape with no corners: Circle.
Commentary: This tests the understanding of "square corners" and the distinct properties of squares, rectangles, and circles. It also encourages discrimination between shapes.
Question 4: Imagine your classroom. a) Name two objects that have a circular face. b) Name two objects that have a rectangular face. c) Name one object that has a square face.
Solution 4: a)
Examples: Wall clock, fan base/guard, base of a water dispenser bottle, a bucket opening. b)
Examples: Door, window, blackboard/whiteboard, textbook cover, student desk top, teacher's table. c)
Examples: Some wall tiles, the face of a dice (if available), a small picture frame.
Commentary: This practical question requires learners to apply their shape recognition skills to their immediate environment, reinforcing the relevance of the lesson.
Community and Environment – Architecture and Structures: Application: Learners can observe and identify squares and rectangles in the construction of their homes, schools, churches, mosques, and local market stalls. Doors, windows, walls, and roof sections (often triangular gables) are prime examples. Circular shapes are seen in borehole covers, water tanks, and road culverts.
Integration: During a community walk or by looking at pictures of local architecture, students can be asked to identify and count the different 2D shapes they see. This reinforces their understanding that geometry is part of their everyday built environment. Culture and Economy – Arts, Crafts, and Trade: Application: Many traditional Nigerian arts and crafts, such as Adire textiles, Aso-Oke patterns, pottery decorations, and mat weaving, incorporate geometric shapes. Market vendors use rectangular tables or square stalls. Products are often packaged in boxes with rectangular or square faces.
Integration: Teachers can bring examples of Nigerian fabrics or crafts to class and ask learners to point out the squares, rectangles, triangles, and circles used in the designs. Discussions can include how these shapes make the items beautiful or functional for trade.
Road Safety and Transportation: Application: Road signs often employ specific 2D shapes to convey information rapidly. Triangular signs typically warn of hazards (e.g., 'dangerous bend ahead'), circular signs give orders (e.g., 'no entry'), and rectangular signs provide information (e.g., 'school ahead'). Vehicle tires are circular.
Integration: Display pictures of Nigerian road signs and ask learners to identify the shapes. Discuss why a circle or a triangle is used for certain signs and how understanding these shapes helps keep people safe on the roads.