In this activity, each student will make their own Hopper Popper, but we suggest they work in pairs when they launch their poppers. Homeschool students can work on their own, but may need a partner to help when it comes time to launch their Hopper Popper. Some teachers choose to have students wear safety glasses for this activity since Hopper poppers can hop high!

Prepare the Chipboard

If you want your students to practice measuring, you can have them cut 3” x 6” rectangles from chipboard before you begin this lesson. If you don’t have time for students to measure and cut rectangles, we recommend you cut the chipboard into 3” x 6” rectangles before class. It doesn’t take long if you use a paper cutter.

Supplies for Open-Ended Exploration (Optional)

At the end of the activity, we suggest that students change one variable to see how this affects their Hopper Popper. For this open-ended exploration, you can supply students with extra chipboard, extra rubber bands of different sizes, or extra rubber bands of different thicknesses. The Teacher Tips printout will help you guide students during this open-ended exploration.

We suggest students work in pairs. Homeschool students can work on their own.

Prepare With Some Engineering Inspiration

We recommend you watch this video of Doug & Pat from the Mystery Science team modeling how to build and improve a bridge. If your students get stuck, you can use this video for inspiration. Our Teacher Tips printout also provides suggestions for guiding students when they are building bridges.

We suggest students work in pairs.

Plan Your Space

The trapeze model will need to hang from the side of a desk or table. We suggest that students move their chairs and sit or kneel on the floor to be able to more closely observe the movement of the model.

Prepare Your String

Cut the string so that each piece is about 2 feet (~61 cm) long. Each pair of students will need two pieces of string.

Build a Test Trapeze

We suggest building one of the trapeze models prior to student testing to ensure that your materials work together. If the string is too thick, the suggested binder clip size won’t be able to hold these in place. You may need to adjust the type of string you use or you can try using larger binder clips.

Set Up Magnet Test Items

The test items should include some metals that are attracted to magnets, some metals that are not, and some non-metal items. At a minimum, students should examine one item from each of these categories. You may want to set up a test item station so that students can explore multiple items from each category.

Cut Up String

Before class, cut up the string so that each student can have some for their experiments.

Teacher Tip

Magnets are fragile, so be careful. If you smack them against each other too hard, they will break. We trust you’ll be gentle with them, but just in case, it can’t hurt to wear safety goggles.

Sort Materials Into Two Piles

Each student will first make a paper door using cardstock, scissors, and a post-it note. Then, students will design a lock for their door using a magnet, paperclip, paper fastener, stickers, and index cards. You may want to sort your materials into two piles for easier distribution.

Be Prepared for Some Troubleshooting

In this activity, students are asked to create something new -- an essential part of the engineering process, but one that may confuse or frustrate them. Below are some of the more common difficulties we found during our own testing, and the solutions we came up with.

• Brads won’t puncture paper: Students may have trouble puncturing the paper with the brad. If this happens, use a sharp pencil to poke a small hole in the paper, then insert the brad.

• Items won’t turn on the brad: The hole probably isn’t big enough. Twist the brad in a full circle a few times to enlarge the hole.

• The magnet doesn’t make the lock move: Every lock will work differently, but it’s typically friction that causes this problem. If a piece of your lock is supposed to move, be sure it can move easily. If it’s attached too tightly, your magnet may not be able to move it.

• Pieces keep getting stuck against one another:

  • If your lock keeps getting stuck, try rounding the edges of the moving parts.
  • If the lock is getting stuck because a piece of paper is bending the wrong way, you can make the paper stiffer by folding it and adding stickers or paper clips to hold it together.

• Walls keep falling down: If you need help getting your wall to stay up, clip the 1-inch fold on the back to a clipboard, or slide it under the edge of a heavy book.