Introduction to the construction zone

Rube Goldberg machines

Rube Goldberg machines.are named after cartoonist Rube Goldberg. They are intentionally over-engineered contraptions designed to perform a simple task through a chain reaction of complex, often humorous steps. They often use simple machines. You can learn more about these in SILO 4.1 'Simple machines'. The following video (1:08) set a world record for being the largest Rube Goldberg machine to feature only pieces from a household air-conditioning unit.

What does it mean to be over-engineered?

Investigating shapes

Building 3D objects

Toothpick and chickpea activity

Chickpeas work really well as connectors for toothpicks. For best results, soak dry chickpeas in water overnight as canned chickpeas are usually too soft and can break apart.

(Image source https://aofradkin.wordpress.com/2017/04/06/the-joys-of-peas-and-toothpicks-for-all-ages/)

Design challenge

Using this newly gained knowledge of shapes, students will work independently to build the tallest structure possible that is able to stand upright on its own. They will then line all their structures up and look at which is the tallest and why it is able to support itself at this great height.

What made the tallest structure so successful? What kind of base did each person choose? Do you notice anything about some famous structures such as the Eiffel Tower? (i.e., what kind of shape do they make going from top to bottom?) How could you have refined your structure to make it more successful for next time? (this is part of the design cycle).

What is an engineer?

This short video (4:29) provides an introduction to engineering and what it means to be an engineer.

Building bridges

Does anyone know what a bridge is? Can anyone name any famous bridges? Can you identify what features most major bridges contain that was discussed in an earlier week (answer, triangles)?

Remember earlier in this unit when we learned about engineers? One type of engineer is a civil engineer. These engineers are responsible for building stable structures – for example, bridges!

The following video (3:45) from SciShow Kids discusses what makes bridges strong.

The following video (3:51) Deysi from Design Squad Global talks about the strength of using triangles in your engineering designs.

Building bridges

Students will endeavour to test this shape theory with the addition of weights. Their goal will be to build a bridge that can withstand a downwards force acting on it. Students will have 20 minutes to build their structure and then we will test each bridge by placing its ends on an elevated surface and layering weights such as books on top until the structure fails. The bridge that remains standing the longest is the winner.

If your bridge failed, can anyone identify the way in which it failed? Why did it fail this way? What did the longest standing structure do successfully?

Popsicle stick challenge

We have learned about building bridges using the strongest shape which were triangles. Does anyone remember what we used to fasten the toothpicks together earlier in this unit? That’s right, chickpeas! How did the chickpeas hold the toothpicks together? For the popsicle stick challenge we are going to use force to hold together a different type of material, that is even stronger than the toothpicks from before – popsicle sticks!

PART 1: Everyone is going to create a structure by weaving together a handful of popsicle sticks. The outline of the panels we are creating have already been put together, using PIN JOINTS to keep the corners in place; your task is to weave popsicle sticks through the center to strengthen the panel through reinforcement which will STABILISE the structure.

The first structure (shown in blue) can can made using six popsicle sticks. This can then be extended into a stronger shape (shown in red) using a total of ten popsicle sticks. 

LEARNING POINT: Wait – with no glue, how are these two center pieces going to stick to the rest of the panel? Well, each popsicle stick is going to be supporting the other by applying a force that is opposite to the next touch point.

Once the bridge is finished, the class can test the strength in a similar way to how the toothpick bridges were tested, to prove the increased strength of the popsicle sticks.This activity demonstrated one way cable ties are useful in linking objects together. Cable ties are also very useful in the design cycle.

There is an old saying that, "A chain is only as strong as its weakest link". What does this mean?

There is another saying advising us to, "Measure twice, cut once". What does this mean?

Making scissor arms

• 4 hole-punched plastic arm pieces
• Cable ties 
• Pin joints 
• Bulldog clips 
• Binder clips

*Give students 20 minutes to build their scissor arm*

Now that everyone is done building their machines, we are going to test them! Your goal is to move as many of the 3D blocks from one desk to the other desk, without dropping them or damaging their shape.

Which fastening mechanisms were most effective – pin joints or cable ties?   What about the materials used on the end of the arm – which best held the delicate blocks and why?

Shapes and their superpowers

Squares

In SILO 2.1 'Shapes and objects' we learned about the properties of circles and how this also applies to cylinders. Earlier in SILO 2.2 'Construction zone' we learned about triangles. Now it is time to look a squares and the idea of being 'square'. Although a square does not have the same structural strength as a triangle, squares are everywhere in classrooms, tables and even boxes thanks to the symmetrical properties of the 90-degree angle. The idea of a building being ‘square’ is a fundamental concept in the construction industry.

Create mechanisms to change the direction of movement using split pins as fixed and floating pivots All pivots can rotate but fixed pivots are held in place by being connected to another object. Floating pivots are free to move. The materials required are card stock, split pins, straws and tape.

It might be helpful to think of your elbows and knees as floating pivots as they can rotate even though your body is free to move at the same time. A fixed pivot is like a boom gate at a car park or hinges on a door. However, in the mechanisms activity (below) where you build a person with arms and legs, the pivots in the same positions as elbows and knees are actually fixed pivots. The arms and legs remain straight while rotating from the shoulders and hips.

Notes: The stick figure can also be made using a cardboard tube or disposable cup instead of the card stock. This will make the end product more like a toy.

Another option for students who are struggling with this activity is to make an analog clock face. This only requires one fixed pin connecting two arms of different lengths to card stock with the 12 numbers drawn on.

More ideas for classroom construction projects

Cardboard is a versatile material for classroom construction projects and it is readily available from old packaging and boxes. As an alternative to connecting cardboard with tape and/or glue, there are now commercial options such as Makedo. Although The SILO Project does not officially endorse any STEM resources, this product is recommended due to the ease of use and safety features as shown in the following video (2:13). 

Moderated self-assessment

Discussions with students around the key components of conceptual topics and how they fit together can generate insights into student achievement.

We welcome your feedback and suggestions

The chief investigator for The SILO Project is Associate Professor Brendan Jacobs, Head of Department STEM Education, University of New England. The SILO Project thrives on incremental improvement so constructive feedback is greatly appreciated. Please contact Brendan via email at bjacobs7@une.edu.au to share your thoughts and recommendations.

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License

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