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Ever wondered why crushed ice seems to cool your drink faster than cubed ice?
Surface area is an important mathematical concept that can help you understand this real-life problem.
In this artistic, real-life lesson plan, students will learn about finding the surface area of rectangular prisms using 3D shape nets. The lesson plan includes guided notes, practice with color by code, and a real-life application of finding the surface area of ice in drinks like lemonade.
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After this lesson, students will be able to:
Convert a given rectangular prism to a 3D shape net
Find the surface area of a rectangular prims
Understand the real-life application of the surface area of rectangular pri
Note: This only covers surface area of rectangular prisms. For volume of rectangular prisms check out my volume lesson plan. For other shapes, check out the extensions section below.
Before this lesson, students should be familiar with:
Basic geometry concepts such as how to find the area of a square, rectangles, and triangles
Understanding of the concept of 2D vs. 3D
Basic understanding of mathematical operations
Pencils
Colored pencils or markers
Surface Area of Rectangular Prisms Guided Notes
Surface area
Rectangular prism
3D object
Net
As a hook, ask students why crushed ice seems to cool their drinks faster than cubed ice. Refer to the last page of the guided notes as well as the FAQs below for ideas.
Use the guided notes to introduce the steps to convert a rectangular prism to a 3D shape net. Walk through the key points of the topic of the guided notes to teach. Refer to the FAQ below for a walk through on this, as well as ideas on how to respond to common student questions.
Use the second page of guided notes to introduce matching nets to 3D objects.
Check for understanding. Have students walk through the "You Try!" section. Call on students to talk through their answers, potentially on the whiteboard or projector. Based on student responses, reteach concepts that students need extra help with. If your class has a wide range of proficiency levels, you can pull out students for reteaching, and have more advanced students begin work on the practice exercises.
Have students practice finding the surface area of rectangular prisms using the practice questions. Walk around to answer student questions.
Fast finishers can dive into the color by code activity for extra practice. You can assign it as homework for the remainder of the class.
Bring the class back together, and introduce the concept of the surface area of ice in drinks like lemonade. Discuss how understanding surface area can help explain why crushed ice cools drinks faster than cubed ice. Refer to the FAQ for more ideas on how to teach it!
If you’re looking for a way for your kinesthetic learners to engage with 3D shape nets, why not have them build emoji and Minecraft characters from 3D shape nets?
There’s different versions depending on your students’ needs:
Emoji nets. Practice finding surface area of 3D shape nets with decimals, fractions, and whole numbers. At the end of the activity, students walk away with an emoji cube.
Challenge: Minecraft nets (whole numbers, fractions). Practice finding surface area and volume of 3D shape nets, and end the activity with a Minecraft character.
If you’re looking for digital practice for finding the surface area of 3D shape nets, try my Pixel Art activities in Google Sheets. Every answer is automatically checked, and correct answers unlock parts of a mystery picture.
There’s different versions depending on your students’ needs:
Rectangular & triangular prisms. Practice these shapes with this spring and St. Patrick’s Day themed activity.
Square & triangular pyramids. Practice these shapes with this spring and Easter themed activity.
A fun, no-prep way to practice finding the surface area of 3D shape nets is Doodle Math — it's a fresh take on color by number or color by code. Each includes multiple levels of practice, and they’re perfect for a review day or sub plan.
There’s different versions depending on your students’ needs:
Right rectangular prisms. Practice these shapes with this Pi Day themed activity.
Challenge: Lateral and total surface area. Want to dive into lateral and total surface area? Try this abstract art themed activity, which is perfect for any time of year.
A rectangular prism is a three-dimensional shape that has six faces, each of which is a rectangle. It is also sometimes referred to as a rectangular cuboid or a rectangular parallelepiped.
Surface area refers to the total area of all the faces of a 3D object, while volume refers to the amount of space that a 3D object occupies. Surface area is measured in square units (such as square meters or square inches), while volume is measured in cubic units (such as cubic meters or cubic inches).
To convert a rectangular prism to a 3D shape net, you will need to follow these steps:
Identify the individual faces of the object: Look at the rectangular prism and identify all of its faces or sides.
Flatten those faces onto a 2D plane: Draw each face of the prism on a flat surface such as paper. Ensure that the shapes are drawn accurately and to scale.
(Optional) Cut and fold the flattened shapes to create the net: Cut out the shapes and fold them along their edges to create a 3D model of the original object.
To find the surface area of a rectangular prism using 3D shape nets, you need to determine the area of each face of the net and then add them all together.
Here's an example:
Identify the faces of the net: A rectangular prism net has six rectangular faces.
Determine the area of each face: Su
ppose the length, width, and height of the rectangular prism are 4 cm, 3 cm, and 2 cm, respectively. The area of each rectangular face can be found by multiplying its length and width. The area of the top and bottom faces is 4 cm x 3 cm = 12 cm². The area of the front and back faces is 2 cm x 3 cm = 6 cm². The area of the left and right faces is 2 cm x 4 cm = 8 cm².
Add up the areas of all the faces: The total surface area of the rectangular prism net is the sum of the areas of all six faces: 2(12 cm²) + 2(6 cm²) + 2(8 cm²) = 48 cm² + 12 cm² + 16 cm² = 76 cm².
If your students need a visual explainer, I recommend this Khan Academy video on finding the surface area of a rectangular prism:
Real-life applications of the surface area of 3D objects include:
Beverage cooling: Understanding the surface area of ice in drinks like lemonade can help explain why crushed ice cools drinks faster than cubed ice. A greater surface area of ice is exposed to the liquid, allowing for faster heat transfer and thus faster cooling.
Packaging design: Understanding the surface area of a package can help manufacturers determine the amount of materials needed to create it, as well as the amount of space it will occupy during shipping and storage.
Heat transfer: Surface area plays a key role in the transfer of heat between objects. For example, larger surface areas can lead to more efficient heat transfer, which is why some cooking tools, such as griddles, are designed with ridges to increase their surface area.
Understanding the relationship between surface area and the cooling process can help explain why crushed ice cools drinks faster than cubed ice. Here are some key points to keep in mind:
Crushed ice has a greater surface area exposed to the liquid. This allows for faster heat transfer and thus faster cooling.
More surface area means more contact with the liquid. This allows for a greater transfer of heat from the liquid to the ice.
Crushed ice is a more efficient cooling agent than cubed ice. This is because it cools drinks faster due to its greater surface area.
By understanding how surface area affects the cooling process, we can better appreciate the science behind why crushed ice is a more effective cooling agent than cubed ice.
Try these 6 free activities for grades 3 - 7.
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