Detective- Mechanical Engineering



Name of Activity

Detective-Mechanical Engineering


Kirsten Jorgensen and Hannah Garflied


rube goldberg, mechanical, simple machines, gears, inclined planes, pulley, lever, wedgem screw


Simple Machines

Grade Level

4, 5


1 Hour Total, 2 Hours Total

Brief Description

Lesson 3 of Detective Engineer: Intro to Different Types of Engineering unit – mechanical engineering.

Lesson Objectives:

-understand what mechanical engineers do and design-become familiar with the different types of simple machines

-create a rube goldberg device

Materials Needed:

LEGO Simple Machines KitExtra Lego Pieces

a few NXT touch sensors

Preparation and Set Up:

Arrange students in pairs with 1 simple machine kit per group


Continuation on the “Detective” Story line that we are following in this unit. Give the next part of the crime. We sent some of the shrapnel  they filtered from the last week and determined that the bomb that exploded in the museum of science was a bomb that was triggered by a button next to the bomb. There were no finger prints on the trigger. Discuss how this is possible? eventually get to Rube goldberb device because they wouldn’t be blown up if they were a distance away and triggered the bomb. What kind of engineer could build this? First we have an open discussion on mechanical engineers-what they do and why this field is different from other types of engineering–moving parts, robotics etc. What is a rube goldberg device? How do they work. Open discussion about what a simple machine is, why we use them, why they’re helpful, what the different kinds are and what their specific uses are (write on board for reference later). Project: Create a rube goldberg device with 2 different simple machines that can trigger a button (NXT touch sensor) from across the desk — has to be far enough away so they don’t blow up Give students 10-15 minutes to develop an idea and have a plan before they start. Hand out simple machines kits  after it is confirmed that they have a relatively good idea of what they are going to build and assist students as needed (how to work a gear box and how to make the certain simple machines because a lot of them have never seen how gears work) Ended up using a second week for this project so they could finish. Had pairs present their projects to the class. Had them talk about their idea and which simple machines they used.


If they finish early, try to have them implement a 3rd simple machine. (only 1 group finished early)

Umbrella Unit/Curriculum (if applicable)

Detective Engineer: Intro to Different Types of Engineering

1 comment on this post.
  1. Christopher Keyes:

    Nazifa Sarawat and I did a similar activity with our JQS class in Fall 2015 for our detective engineering unit.

    Our class had experience with simple machines from other science classes, so we decided to give them an extra challenge. We brought in a wide assortment of materials from the CEEO, such as PVC pipe, string, lego wheels, cardboard boxes, paper tubes, and more, and had groups of students try to reverse-engineer the heist. The story connection was that if investigators knew how the generator was stolen, they might have a better idea of who to look into for suspects.

    We emphasized both planning and redesigning in this lesson, by having students plan individually and then as a group. Since they were working with such makeshift materials, many groups struggled to get their designs to function, so we encouraged adaptation. It was helpful to remind them that it was okay if their simple machines didn’t lift the load (we used water bottles) very high, because they were really making a small-scale model.

    We ended up having to extend this activity to two weeks as well. At the end of the second week, we had each group present to the whole class their simple machine design and give a demo if possible. This was the first time we introduced the sharing step of the engineering design process.

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