Montessori constructive triangles are so much fun for hands on geometry learning. I love how the simple shapes encourage creative math exploration.
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I’ve been wanting to buy the wooden triangles for a while but Montessori materials can be a bit expensive. Fortunately, these shapes are easy and inexpensive to make at home. You are probably thinking that you should make them out of cardboard. But NO!
Make them out of craft foam sheets!
Super duper easy to cut out, and durable. No x-acto knife required! Also because they are flexible you don’t have to worry about your kids bending them in half and creasing them up.
My favorite is the batch of 12 blue scalene triangles. I love how versatile they are. Even if you are not specifically following the Montessori method (as we are not), they are terrific for free exploration and an excellent sensory experience in making shapes and the science of geometry. Kiddo really enjoyed experimenting with them.
Montessori purists may be horrified at my lack of structured presentation of the materials! I will not deny that I may be a bit lazy when it comes to that! In any case, my son loves playing with them, and I’m sure he benefits from exploring our homemade Montessori triangles, even if it’s not according to the “rules”.
A scalene triangle is a triangle with a right angle, and three sides of different lengths. You could make any number of interesting Montessori inspired triangle sets as long as all 12 scalene triangles are the same size. It would be fun to experiment!
Lucky you, I have a template for you to use!
Click on the image below to get the printable Montessori scalene triangle template:
Don’t forget the craft foam!
Update: I found this triangle set which is pretty affordable!
Find 35 more make your own puzzle ideas!
Anna - Three Sneaky Bugs says
I love the idea of craft foam for this. Matt board would have gotten beat up too quickly. Seth does go to a montessori school and I leave the structure to them. At home it's just free exploration. I like giving him that balance to create at home.
Bona Fide Mama says
yes, i am crazy about anything that will help me use up this blasted craft foam i got stuck with!
Valerie @ Frugal Family Fun Blog says
I like your less rigid approach to this. It's like Montessori for the rest of us!
Tan Family says
Oh, neat idea! I love your blog. 🙂 –Jennifer syrendell.blogspot.com
Fun Mama - Deanna says
I think the rigidity is one reason I'm drawn to Waldorf. It seems much more “fluffy” and open to interpretation. And requires less direction for me. Or maybe I don't understand it either.
Christy says
So very cool! Thanks. I agree with you on the rigidity; I'm not organized enough for that. Maybe I just don't understand it completely, but it seems a bit robotic to me.
Sofi says
This is neat, thanks for the great idea to use foam! Just a quick note: a scalene triangle is just a triangle with sides of three different lengths. A “right scalene triangle” will have to have a right angle, but just a “scalene triangle” doesn’t have to have one. (<— math teacher can’t help herself 😂) Will be making these tomorrow with my kid!
Erica says
Thanks for the clarification!
Stacey says
Hi! I discovered your blog during this quarantine and love love love it, especially your book recommendations. This looks like something my 6 year old would like and I have sheets of felt with which to make the triangles. But then what? Do i ask him to make shapes, or do i show hime shapes he could make and then he figures out how to make them? Thanks for your guidance and thanks so much for these resources.
Erica says
Hi Stacey! So glad you have liked the blog’s resources. What I did was just let my kid explore the triangles. He was interested enough in them for it to be self-led. Although I believe I also would sometimes leave them in shapes and patterns for him to find – thus sparking a bit more exploration. There is an official Montessori way to use the triangles. I never did that but there are lots of videos on YouTube showing the official way. I hope this helps!
Mary Moore says
Hi, I’d like to specify that scalene triangles don’t need to be right angled triangles. They are scalene if all three sides are different lengths.
Erica says
Oops! Yes, indeed you are correct.