| Full lesson | Create for a teacher a set of content for giving a lesson, beginning with the lesson plan. Each new block of materials must begin with an H1 heading (other subheaders must be H2, H3, etc). When you describe required pictures, write those descriptions in curly brackets, for example: {A picture of a triangle} |
| Which subject | Mathematics |
| What topic | Perimeter of triangle |
| What length (min) | 40 |
| What age group | Year or Grade 8 |
| Class size | 11 |
| What curriculum | Kerboodel |
| Include full script | |
| Check previous homework | |
| Ask some students to presents their homework | |
| Add a physical break | |
| Add group activities | |
| Include homework | |
| Show correct answers | |
| Prepare slide templates | |
| Number of slides | 5 |
| Create fill-in cards for students | |
| Create creative backup tasks for unexpected moments |
Perimeter of a Triangle
Year 8
Mathematics
11 Students
This lesson plan aligns with the Kerboodle national curriculum standards for Year 8 Mathematics.
| Step Number | Step Title | Length (mins) | Details |
|---|---|---|---|
| 1 | Introduction to Perimeter | 5 | Briefly explain the concept of perimeter, focusing on triangles. Use visual aids to enhance understanding. |
| 2 | Explanation of Formula | 10 | Introduce the formula for calculating the perimeter of a triangle (P = a + b + c). Provide examples. |
| 3 | Distribution of Printable Cards | 5 | Hand out cards that students will use for the activity, instructing them on how to fill them out during the lesson. |
| 4 | Guided Practice | 10 | Lead students through several example problems, calculating the perimeter of given triangles together. Use the cards to engage students. |
| 5 | Independent Practice | 5 | Allow students to solve related problems independently using their cards, moving around to provide support as needed. |
| 6 | Collection of Cards | 3 | Collect or randomly check students' filled cards to assess understanding without presentations. |
| 7 | Homework Assignment | 2 | Assign homework related to perimeter calculation (details not specified). Clarify due date and submission instructions. |
"Good morning, everyone! Today, we’re going to explore a really interesting topic in mathematics: the perimeter of a triangle. Does anyone know what perimeter means?
Correct! The perimeter is the distance around a shape. In the case of a triangle, the perimeter is the total length of all three sides.
[Draw a triangle on the whiteboard.]
Here, we have a triangle. Let’s label the sides as A, B, and C. If I were to walk around this triangle, I would need to walk the length of side A, then side B, and finally side C.
So, the perimeter is simply the sum of these three sides. Let’s keep this idea in mind as we move on to learn how to calculate it!"
"Now, let's talk about how we calculate the perimeter of a triangle. The formula is pretty straightforward. It’s P = a + b + c.
[P = a + b + c is written on the whiteboard.]
Here, ‘P’ stands for perimeter, and ‘a’, ‘b’, and ‘c’ represent the lengths of the triangle’s sides.
Let’s go through an example together. Suppose we have a triangle where side A is 5 cm, side B is 7 cm, and side C is 3 cm.
[Write the example on the board.]
If we apply our formula: P = 5 + 7 + 3.
Let’s solve it together. What do we get?
Exactly! 15 cm. So, the perimeter of this triangle is 15 cm.
Great! Now a quick question: Why do you think knowing how to calculate the perimeter is important?
Exactly, it helps in real-life situations such as determining the amount of fencing needed for a garden or fabric for a triangular tent."
"Next, I’ll be handing out some printable cards to each of you.
[Hand out the cards.]
These cards have the formula for perimeter on one side and some triangle diagrams on the other. I want you to use these cards to fill in the side lengths and calculate the perimeter of each triangle diagram provided.
You can use the example we just solved to help you. Ready? Great! Start filling them out!"
"Now that you have your cards, let's work through some triangle examples together.
[Draw another triangle on the whiteboard, with different lengths.]
This time, let’s say side A is 4 cm, side B is 6 cm, and side C is 5 cm.
What would our formula be?
That’s right! P = 4 + 6 + 5.
Let’s solve that. What do we get?
Fantastic! The perimeter is 15 cm again! Now, I'm going to show you a few more triangles, and I want you to calculate the perimeter using your cards as we go.
[Continue with more examples, engaging with different students to provide answers.]
Excellent work, everyone! You’re really getting the hang of this."
"Now, I’m going to give you a few minutes to work independently.
Take your cards and find the perimeter for the triangles printed on them.
Remember to use the formula we discussed!
I’ll be walking around to help if you need any assistance. Go ahead and start solving!"
"Alright, time’s up! Please pass your cards to the front or place them in the collection box.
I’ll be quickly checking how you solved the problems, and I may randomly ask a few of you about your calculations. This is just to assess how well we understood today’s topic without needing full presentations.
Thank you for your cooperation!"
"For your homework, I’d like you to complete the worksheet provided that has some additional problems about calculating the perimeter of triangles.
Be sure to review the formulas we covered today!
The homework is due on Friday, and you can submit it in class or email it to me if that’s easier for you.
If you have any questions about the assignment, please feel free to ask after class."
"To wrap up, let’s quickly recap what we learned today. We discussed the perimeter of a triangle, how to calculate it using our formula, and why it's important in real life.
Does anyone have any questions or need clarification on any part of today’s lesson?
Great! Thank you for your hard work today, and don’t forget about the homework. Have a fantastic rest of your day!"
Define what the perimeter of a triangle is in your own words.
If side A of a triangle measures 8 cm, side B measures 5 cm, and side C measures 7 cm, what is the perimeter of the triangle? Show your calculations.
Why is it important to know how to calculate the perimeter in real-life situations? Provide at least two examples.
A triangle has a perimeter of 24 cm. If side A is 10 cm and side B is 9 cm, what is the length of side C? Show your working.
Create your own triangle with side lengths of your choice (all sides must be less than 10 cm). Calculate the perimeter of your triangle and provide the dimensions you used.
Draw a triangle with a perimeter of 30 cm. Label the sides and show how you arrived at that total.
Explain how you would use the formula P = a + b + c to solve for a missing side of the triangle. Include an example with your explanation.
If the perimeter of a triangle is 18 cm and one side is doubled in length while keeping the others the same, what will happen to the perimeter? Explain your reasoning.
The perimeter of a triangle is the total distance around the triangle, calculated by adding up the lengths of all three sides.
Perimeter = A + B + C = 8 cm + 5 cm + 7 cm = 20 cm.
Knowing how to calculate the perimeter helps in situations like determining how much fencing is needed for a garden or how much material is necessary for making a triangular tent.
If P = 24 cm, A = 10 cm, and B = 9 cm, then C = P - (A + B) = 24 cm - (10 cm + 9 cm) = 5 cm.
Example: Let’s say side A = 3 cm, side B = 4 cm, and side C = 2 cm. Perimeter = A + B + C = 3 cm + 4 cm + 2 cm = 9 cm.
Example triangle: Side A = 10 cm, side B = 10 cm, side C = 10 cm. Perimeter = A + B + C = 10 cm + 10 cm + 10 cm = 30 cm.
If we know two sides of a triangle, we can isolate the missing side by rearranging the formula. For example, if P = 15 cm, and A = 5 cm and B = 4 cm, then C = P - (A + B) = 15 cm - (5 cm + 4 cm) = 6 cm.
If one side is doubled (e.g., side A becomes 2A), then the new perimeter will be (2A + B + C). The perimeter will increase by the length of one side (the additional A).
| Question | Answer |
|---|---|
| What does the term 'perimeter' mean? | |
| How do you calculate the perimeter of a triangle? | |
| If side A is 5 cm, side B is 7 cm, and side C is 3 cm, what is the perimeter? | |
| Why is it important to know how to calculate the perimeter in real life? | |
| What is the formula for calculating the perimeter of a triangle? | |
| If side A is 4 cm, side B is 6 cm, and side C is 5 cm, what is the perimeter? | |
| What will you use the printable cards for during the lesson? | |
| How can knowing the perimeter help in practical situations? | |
| What should you do with the cards once you finish the activity? | |
| What is the homework assignment related to today's lesson? |