Make a Da Vinci Bridge Using Household Items (with 3D Printable Option)

Leonardo Da Vinci invented the self-supporting bridge I'm going to show you how to make here.

It can be built using no notches, glue, nails or any kind of fastenings, relying on only friction and gravity to hold itself together!

This is such a fun activity for kids of all ages and is best done in groups of at least 2 or 3 so works nicely as a team building, cooperative task too!

You can build this whole bridge using items you probably have in your home or classroom already!

Great for lessons on gravity, friction, structural strength, Da Vinci himself and just for getting kids excited about science!

This is really up to you and will depend a little on age group and how many kids you're working with but you can use any of the following:

• The 3D printable files I'll provide
• Straws
• Pencils
• Skewers
• Bamboo Cane
• Planks of Wood (you could even make a life size bridge that your group can walk over)
• Anything else that you can find of a similar shape to the aforementioned!!

You'll need at least 15 rods or planks of equal sizes!

If you have access to a printer:

I understand that 3D printers are becoming more commonplace in schools and at home and, as it's a major hobby of mine, I made 3D printable models for this in case you want to add another layer to the learning!

There are 2 files here, there are smooth rods and rods with shallow notches (both have a flat bottom just for ease of printing) - as mentioned in the intro, you can build this with no notches or any kind of fastening so if you're looking for a challenge, go ahead and just print 15 of the smooth rods otherwise you'll want 5 smooth and 10 notched.

If you're doing this on your own, with young children or just looking to down the difficulty:

If printing, the notches certainly help you line things up while being shallow enough to not actually secure the rods in place so still demonstrate the concept well.

If not printing, you can achieve a similar result by tying loom bands around the ends and in the middle of your rods (in roughly the same places as I have notches).

Teaching moment: This is a great opportunity for an extra teaching moment - get them thinking about why the notches or rubber bands might make this easier, or why it might be more difficult without - why might you need rubber bands on a pencil but planks of wood work fine without? This is a great time to explore the concept of friction!

To make it easier to follow, I've labelled the rods with notches as Bs in blue (this would apply to any rods with rubber bands etc too) and the smooth rods are As in white - I also coloured the ends of the notched rods orange as I know it can get a little confusing to look at as we add more and more rods.

Please don't be intimidated, it looks complicated and scary but is actually a very simple build!

If you're using all smooth rods you don't need to worry about As and Bs at all, just follow the general shape.

Note: If using all smooth rods, this really is a 2 person (at least) job, you'll need more than 2 hands to hold everything in place as you build which is why it makes such a fun group activity!

Teaching moment: It might be interesting to give your kids or students the building materials with no instructions first and tell them to try and make a bridge! Give them a few minutes to just play around before starting to show them how to do it - this always increases the wow factor a little and highlights how incredible Da Vinci's thinking really was!

Let's get building!

• Take 2 smooth rods and lay them flat (these are 2A and 3A)
• Lay 2 of the notched rods on top to form a square (these are 1B and 2B)
• Place a final smooth rod across the centre (1A)

Now we're going to add 2 more of the notched rods

To help I've labelled the new rods in a brighter colour and circled them in the pictures.

• Holding 2A, gently lift the right side of the square you built in the last step
• Pass a notched rod (3B) through the gap between 1A and 2A and hook it over 1A and under 2A
• Repeat this process with a second notched rod (4B)

We'll now do exactly the same thing on the left side of the bridge

• Holding 3A, gently lift the left side of your bridge
• Pass a notched rod (5B) through the gap between 1A and 3A
• Hook it over 1A and under 3A
• Repeat this process with a second notched rod (6B)

• Take another smooth rod (4A) and simply slide it under 3B and 4B as pictured

Here we'll use the same process from steps 3 and 4

• Lift the right side of your bridge holding the smooth rod we added in the last step (4A)
• Pass 1 notched rod (7B) through the gap between 4A and 2A
• Hook it over 2A and under 4A
• Repeat with a second notched rod (8B)

• Slide a smooth rod underneath 5B and 6B on the left side of your bridge (5A)
• Holding the rod you just added (5A) lift the left side of your bridge
• Pass a notched rod (9B) through the gap between 3A and 5A
• Hook 9B over 3A and under 5A
• Repeat with a second notched rod (10B)
• Straighten out any rods that moved around as you built

That was the last stage of the building!!

Now to test it out and see what we've learnt!

Fantastic! You (or the little ones you were directing) have built a bridge!

Now what?

This is where you realise how clever this bridge really is!

Ask your students (or your kids, or yourself) 'Does this bridge look very strong?'

Chances are the answer you'll get is NO! It looks wobbly and rickety and like it'd fall to bits as soon as you nudged it, right?

Now put something on your bridge - Preferably something with a decent bit of weight to it and ask the same question again.

The absolute genius of this bridge is that, because of the way the rods all interlock, when a load is added, the weight is distributed across the whole bridge, the force exerted from the added object pushes the rods together and makes the whole bridge more structurally solid - you/they should notice that the rods no longer slide around so easily and the bridge feels more robust.

For a final learning moment (and if you're not concerned about keeping the bridges) see how much force it can withstand by adding more and more weight or simply by pushing down on the bridge and observe how it changes - the rods themselves can only withstand so much force and will eventually bend and break at some point - this is yet another chance to explore the why behind that!