Roof Rehab (Roof truss) Classroom Activity

Transcription

1 Roof Rehab (Roof truss) Classroom Activity The Classroom Activity introduces students to the context of a performance task, so they are not disadvantaged in demonstrating the skills the task intends to assess. Contextual elements include: an understanding of the setting or situation in which the task is placed, potentially unfamiliar concepts that are associated with the scenario, and key terms or vocabulary students will need to understand in order to meaningfully engage with and complete the performance task. The Classroom Activity is also intended to generate student interest in further exploration of the key idea(s). The Classroom Activity should be easy to implement with clear instructions. Please read through the entire Classroom Activity before beginning the activity with students to ensure any classroom preparation can be completed in advance. Resources needed: Paper and writing tool for each student 1 Some method of displaying images 2 Whiteboard or other method of recording student responses Resources Provided Resource Documents o Figure 1. Roof Pitch o Figure 2. Roof Trusses o Figure 3. Ridgeline Image o Figure 4. Roof Truss Designs Learning Goal: The student will understand the context of the key ideas related to the topic of the Classroom Activity, including: o Roof Construction o Steps and considerations involved in constructing a roof or roof truss The student will understand the following vocabulary: o Plywood: A strong flat board. Traditionally plywood is made in 4-foot by 8-foot sheets with varying thicknesses o Roof Truss: A rigid frame designed to support the weight of a roof o Roof Frame: The network of roof trusses used to support a roof covering o Roof Pitch 3 : The steepness of a roof o o Roof Decking: The surface, usually plywood, used to cover the roof frame Various names for the wood used to construct trusses: beam, brace, chord, joist, lumber, post, rafter, strut, web member Definitions are provided here for the convenience of facilitators. Students are expected to understand these key terms as they arise in the context of the task, not to be able to recite the definitions. 1 Students who need an accommodation may use their preferred tool for writing. 2 Instead of displaying Figures 1, 2, and 3, the images can be used as handouts for students. 3 Roof Pitch is defined in this classroom activity (and the related performance tasks) to be the same as the roof slope. While not all sources agree on this definition, it is commonly used by practitioners (like home inspectors) and therefore is defined in this way for purposes of this activity. 1

2 Roof Rehab Classroom Activity [Purpose: The facilitator s goal is to engage students in the mindset and language of a person new to roof construction and roof truss construction.] Facilitator says: Today we are going to discuss roof construction to prepare for the Roof Rehab Performance Task. Imagine that you and several classmates have volunteered to help build roofs for several homes. To get ready for this task, we will learn about the vocabulary and concepts needed in your new role as a volunteer roofer. [Facilitator displays and describes Figure 1 Roof Pitch graphic.] [Note: For students who are visually impaired, describe the picture orally: Figure 1 shows three houses. The roof of each house has a different level of steepness, or pitch. The two halves of the roof come together at different angles because of the different levels of steepness. The two halves of the first roof create an angle that is about 110 degrees. The two halves of the second roof create an angle that is about 75 degrees. The two halves of the third roof create an angle that is about 160 degrees. (Facilitator should demonstrate the steepness of the roofs with their hands, or a piece of paper, or a folder, and have the student feel them).] Facilitator says: Roofs come in all shapes and sizes. Why do some roofs seem very steep, and others seem very flat? [Allow students to answer. Discuss that the steeper the roof, the easier it is for snow and branches to slide off, but the surface is more dangerous to stand on and vice versa.] Facilitator says: The steepness of a roof is called the roof s pitch. What is the term in math that we use to define steepness? [Allow students to answer. Discuss that pitch, as used in the upcoming performance tasks, is really another word for slope.] 2

3 [Facilitator displays and describes Figure 2 Roof Trusses graphic.] [Note: For students who are visually impaired, describe the picture orally. Figure 2 shows a building with a partially constructed roof. There are long pieces of wood, nailed together in the shape of triangles. These triangles are evenly spaced on the top of the building, and they form the frame for the roof.] Facilitator says: What do you notice about the shape of the roof? [Allow students to respond. Possible responses include the top pieces are triangular, the top pieces are evenly spaced, and the building is rectangular.] Facilitator says: Does anyone know what these triangular sections in the roof are called? [Allow students to respond. Lead students to understand that each triangular section is called a roof truss.] Facilitator says: Each roof needs several roof trusses. All of the roof trusses together form the roof frame. Why is it important to have several trusses in a roof frame? [Allow students to respond. Possible responses include: to keep the roof from sagging, to make the roof strong, and to support the weight of the roof.] Facilitator says: The pieces of wood that make up the roof trusses are called by many different names. Does anyone know any of the names? [Allow students to respond. List the student responses on the whiteboard (or other method of recording student responses). When students are finished, add these terms if they were not mentioned: beam, brace, chord, joist, lumber, post, rafter, strut, and web member.] Facilitator says: The wood used in building roofs is called by many different names. For this performance task, you do not need to know all the different names; you only need to know that all these names refer to the pieces of wood that form a roof truss. 3

4 [Facilitator displays and describes Figure 3 Ridgeline graphic.] Ridgeline [Note: For students who are visually impaired, describe the picture orally. Figure 3 shows a rectangular building with a roof frame on top. A line is drawn across the top of the triangular shaped trusses, along the peak of the roof. This line is labeled ridgeline. ] Facilitator says: The ridgeline of the roof is along the top of all the trusses. Why do you think it is called a ridgeline? [Allow for student answers. Possible responses include: it is the peak of the roof, and a ridge is the top of a mountain and this is the top of the house.] Facilitator says: There are many different roof truss designs. [Facilitator displays and describes Figure 4 Roof Truss Designs graphic.] [Note: For students who are visually impaired, describe the picture orally. Figure 4 shows two sample roof trusses. Each truss is large triangle with extra struts inside it to create more support for the roof. The extra struts create two different designs in the two triangles. The first truss has four struts inside creating 5 smaller triangles. The second truss has three vertical struts inside creating a symmetrical pattern with a triangle and a trapezoid on each side. There are short vertical lines underneath and at the outer edges of the triangular trusses. These represent where the trusses are attached to the walls of the building.] Facilitator says: Here are two examples of roof truss designs. Does anyone know specific names of any roof truss designs? [Allow students to respond. Write any responses on the board. There may be no responses from students; this is not a common topic. When students are finished, add these names if they were not mentioned: bowstring, cantilever, double cantilever, hip, king post, queen post, scissors, and vault.] Facilitator says: Each of these is constructed with a different design. For this performance task, you do not need to know the differences; you only need to know that there are different names for different types of trusses. 4

5 [Facilitator displays and describes Figure 5 Roof Decking graphic.] Plywood Trusses [Note: For students who are visually impaired, describe the picture orally. Figure 5 has several triangular trusses evenly spaced to form the frame of the roof. This frame is partially covered by flat rectangular pieces of wood.] Facilitator says: Once the frame is built, plywood is nailed down to cover it. Plywood is a strong, flat board. It usually comes in 4 foot by 8 foot pieces. When plywood is used to cover a roof frame, it is called decking. Facilitator says: Once the decking is on the frame, the roofing material is added to finish the roof. Optional Discussion Question: What information might be necessary in order to build a roof? [Allow students to respond. Possible responses include: which type of truss, the steepness of the roof pitch, and the dimensions of the building.] Facilitator says: Are there any questions? [Allow for student questions.] Facilitator says: You are now ready to complete the Roof Rehab Performance Task. 5

6 Resource Documents Figure 1. Roof Pitch [Picture Description: Figure 1 shows three houses. The roof of each house has a different level of steepness, or pitch. The two halves of the roof come together at different angles because of the different levels of steepness. The two halves of the first roof create an angle that is about 110 degrees. The two halves of the second roof create an angle that is about 75 degrees. The two halves of the third roof create an angle that is about 160 degrees.] 6

7 Resource Documents Figure 2. Roof Trusses [Picture Description: Figure 2 shows a building with a partially constructed roof. There are long pieces of wood, nailed together in the shape of triangles. These triangles are evenly spaced on the top of the building, and they form the frame for the roof.] 7

8 Resource Documents Figure 3. Ridgeline Image Ridgeline [Picture Description: Figure 3 shows a rectangular building with a roof frame on top. A line is drawn across the top of the triangular shaped trusses, along the peak of the roof. This line is labeled ridgeline. ] 8

9 Resource Documents Figure 4. Roof Truss Designs [Picture Description: Figure 4 shows two sample roof trusses. Each truss is large triangle with extra struts inside it to create more support for the roof. The extra struts create two different designs in the two triangles. The first truss has four struts inside creating 5 smaller triangles. The second truss has three vertical struts inside creating a symmetrical pattern with a triangle and a trapezoid on each side. There are short vertical lines underneath and at the outer edges of the triangular trusses. These represent where the trusses are attached to the walls of the building.] Figure 5. Roof Decking Plywood Trusses [Picture Description: Figure 5 has several triangular trusses evenly spaced to form the frame of the roof. This frame is partially covered by flat rectangular pieces of wood.] 9