DIY: Montessori Red and Blue Number Rods
Here is a recent addition to our homeschooling math sessions : the Montessori red & blue large number (metric) rods.
The rods can be used to help children with numbers from 1 to 10, but my children already know numbers up to … well, I think they got the idea that infinity exists. I built them in the idea that they could use them to visualize and compare sizes. Plus, I’ll let them play freely with them and come up with whatever they like with them.
Usually, you can pay up to 30-40 USD to get them new (I’ve even seen them at 95 USD!) and the cost drops down to about 15 USD when they are old and beaten up.
I made these for something like 2-3 USD (I already had leftover paint from other projects on hand so I didn’t need to buy new pots).
The rods are very easy to make.
What you will need:
- Wooden square rods; I used 1,5cm wide wooden rods though I think the usual size for the “official” Montessori material is 2,5cm wide rods
- Some kind of saw (jig saw, scroll saw, circular saw, hand saw… anything will do).
- Children’s furniture paint, blue and red (or any other color if you want to wander your own path)
- Masking tape
- Ruler/measuring tape, pencil
You will need to cut out the following lengths: 100cm, 90cm, 80cm, 70cm, 60cm, 50cm, 40cm, 30cm, 20cm and 10cm.
That makes 5,5m of rod in all. The rods I found were about 2,5m long, so I got three rods.
You need to start by planning out the cuts you will need to make on your full length rods so that you don’t end up with two small separate pieces that should be together and also to minimize waste. Think about pairing the longer lengths (90cm, 80cm) with the shorter lengths (10cm, 20cm) to minimize waste.
Oh and by the way: you will prefer to cut a little too long and have to sand it down than too short and have to stick with it (or redo it).
When all the rods are cut to size, you will want to start marking off every 10cm of each rod. Do this precisely. Precisely!
Choose a color to start with, either blue or red and mark off each section of that color with masking tape. You can check out my tip for placing masking tape straight all around objects in my last post (Cardboard Pirate Spyglass).
Paint inside each section and set to dry.
When the first color is dry, do the opposite and put masking tape all around the rods to mark off the other color sections. Paint and let dry.
You could also paint the whole rod with a first color then when dry mark off the sections for the second color and paint inside.
That’s it for the classic Montessori Red & Blue Number Rods.
In addition to the classic set, I made an second 100cm rod with the centimeters marked off. That was time consuming but I think it was worth it.
To make the additional 100cm rod with the centimeters marked off, use 1cm wide masking tape and place it very precisely every other centimeter. To do so, start by marking off every 10 cm then inside these 10cm marks, mark off every 1cm. By starting with the 10cm marks you don’t go off track because of micro imprecisions you can get while marking every 1cm.
Then, paint the visible parts of the first 10cm with one color then switch to the other color for the next 10cm (see picture of the striped rod).
When the paint is dry, mark centimeters and millimeters on the rod with a pen.
Voilà, it’s done. Place it in your “classroom” or on a shelf the children can reach and you have it.