Lesson: R.J.'s Invention

Distribute or digitally share the “Nets” template. Tell students that these images are nets, sets of 2-dimensional (2-D) shapes that, when folded, form the surfaces of 3-dimensional (3-D) shapes. Have students analyze the nets and ask them to think about the number and shapes of each net’s 2-D parts. See if they can predict what 3-D figure each net will fold up into. Then play the instructional math video “Understanding Nets.”

Tell students that they will be learning about an entrepreneur who invented a helpful tool. Play the video. Then hold a class discussion using the following questions:

• What did R.J. invent? (R.J. invented a finger guard that protects fingers while chopping up food.)

• Why did R.J. invent Tip Tough? (R.J.’s dad is a chef. He would have cuts on his fingers and once needed stitches. R.J. thought his invention would help chefs like his dad.)

• What selling points does R.J. introduce to help customers want to buy the Tip Tough? (It’s American made, it’s dishwasher safe, it’s durable, and you can use it for other purposes, such as opening packages.)

Have volunteers read paragraphs of the article aloud. Then distribute or digitally share the “Analyze Graphic Information” literacy skill sheet. Read the introduction aloud and go over the headers of the chart. Tell students that, as a class, they will choose the three graphics that they will use to fill out the skills sheet. Have each student look at the graphics and read their captions individually. Then have students vote on the three graphics that they think add the most value to the article. As a class, fill out the chart for the top three graphics the class chose.

Distribute or digitally share grid paper. Read through the introduction of the “Prototypes With Nets” box on page 14. Then read question 1 aloud. Ask: Look at the dimensions listed in question 1. Look at your grid paper. What scale might we want to use in making our nets? (Depending on the size of the grid, you may want to have one unit represent ¹/₈ of an inch or 1 inch, etc. Have students discuss what makes the most sense for their paper.) Then have students draw their nets for question 1 individually. Let them share their drawing with a partner or small group to check their work. Have each person explain why they drew the net the way they did. For question 2, have students work independently. Select a few volunteers to share and explain their net drawings to the class.

Have students try to make as many nets of a cube as possible. Provide each student with a square tile or outline, which they can trace to make each cube’s face. After they draw each net, have them cut it out to see if it in fact folds into a cube. See all 11 possible nets at: mathforum.org/library/drmath/view/54682.html or at the end of the video lesson.

Have students find 3-dimensional items around their homes. They can draw nets of these 3-D items on scrap pieces of paper. Give students two options in doing this. They can either 1) trace the sides of the object in order to draw the net, or 2) measure the object and then use those measurements to draw the nets. Have them then cut out the nets and fold them up to prove that they correctly drew them. To help students with this task, distribute or digitally share the “Your Turn: Create Your Net” skills sheet.