UNIT: CATAPULT

ACT-Based English: Crafting a Persuasive Engineering Proposal

OBJECTIVE:

Students write a proposal to improve a catapult’s design.

Materials Needed:

Research articles

Writing templates

Student Directions:

Goal:

You will research, plan, and write a persuasive proposal that recommends a structural improvement to a catapult. Your writing will include scientific evidence, mathematical reasoning, and engineering justification—just like real engineers do when presenting a new design idea.

PART 1: PLAN & RESEARCH

Step 1: Analyze the Current Catapult Design

Review the current catapult design used in class (or in your project).

Note the materials used, the arm length, base structure, launching mechanism, and firing consistency.

Step 2: Identify a Possible Improvement

Choose one modification you think would improve the catapult’s performance (e.g., extend launch distance, improve aim, increase durability).

Consider: Can you change the angle of release, tension force, base stability, or arm length?

Step 3: Gather Evidence

Use class data, physics principles, and/or outside research to support your improvement idea.
Look for information related to:

Projectile motion

Force and tension

Energy transfer (potential → kinetic)

Engineering design principles

PART 2: WRITE YOUR ENGINEERING PROPOSAL

Step 4: Organize Your Proposal Using the Template

Your proposal should include the following sections:

Introduction

Briefly explain the purpose of the catapult project.

State the goal: improving performance through redesign.

Proposed Modification

Describe the specific change you want to make.

Include diagrams or models if applicable.

Scientific Justification

Use physics and/or math concepts to explain why this change will help.

Include specific data (from your class tests or research) that support your claim.

Real-World Engineering Connection

Explain how engineers justify changes in design.

Make a connection to how design testing and analysis lead to better outcomes.

Conclusion

Summarize your argument and restate how your proposed change will improve the catapult.

PART 3: PEER REVIEW & DISCUSSION

Step 5: Share & Reflect

Exchange proposals with a classmate for peer feedback.

Then, participate in a class discussion or written reflection:

How do engineers justify improvements?

Why is it important to support ideas with evidence?