How Many Triangles? 3

A Mathematics Lesson Starter Of The Day

The animation showing all of the triangles, one by one, is available above when you are signed in to your Transum subscription account. If you do not yet have an account and you are a teacher or parent you can apply for one here.

A Transum subscription also gives you access to the 'Class Admin' student management system, many more teaching resources and opens up ad-free access to the Transum website for you and your pupils.


Share

Topics: Starter | Combinations | Problem Solving | Shape

  • B Unit, Texas
  •  
  • There are 39, not 37
  • Ryan Ames, Edmonton
  •  
  • I count 51
    Not double counting anything
    and remembering that a triangle is just that three angles in which all angles together equal 180 and there is a bunch in there that are not right angles... Would love to know the correct answer though.
  • Ricardo Estopier-Ayala, Strake Jesuit College Prep, Houston, Texas
  •  
  • The correct answer is 37 triangles:
    There are:
    12 single triangles
    12 triangles composed of 2 single triangles
    6 triangles composed of 3 single triangles
    6 triangles composed of 4 single triangles and
    1 triangle composed of 6 single triangles.

    - The triangles composed of 3 single triangles were the hardest to find, but u can use the giant(composed of 6 single triangles) triangle to find them; they are all contained in it.
    - The triangle composed of 4 single triangles are the same triangles as the ones composed of 3 single triangles, except for the fact that they have just added one triangle to the end.
    - I am unsure how to respond to the person who found 51 triangles other than to say that he/she might have confused the definition of a triangle: A plane geometric figure with three angles and three sides.
  • Australia Class, Preston, Lancashire, England
  •  
  • Our class found different ways and strategies to solve this puzzle. We found 37 triangles and we enjoyed it! Thank you.
  • Mr Kavanagh's Fifth Class, Cork, Ireland
  •  
  • Most of the class got lower numbers than 37. The teacher found 27 and when we looked at the answer we realised that there were 37. Abbie got the closest with 30.
  • Transum,
  •  
  • As you can see by clicking on the button underneath the title at the top of this page we have provided a dynamic answer to this question. The challenge is for pupils to show their solution in a clear, organised way of their own. It could be a static series if diagrams or they too may decide to show their solutiion in a dynamic way using the animation tools of PowerPoint, Prezi or similar. Feel free to send Transum any examples of your pupils' work, we may post them on this page.

How did you use this starter? Can you suggest how teachers could present or develop this resource? Do you have any comments? It is always useful to receive feedback and helps make this free resource even more useful for Maths teachers anywhere in the world.
Click here to enter your comments.

If you don't have the time to provide feedback we'd really appreciate it if you could give this page a score! We are constantly improving and adding to these starters so it would be really helpful to know which ones are most useful. Simply click on a button below:

Excellent, I would like to see more like this
Good, achieved the results I required
Satisfactory
Didn't really capture the interest of the students
Not for me! I wouldn't use this type of activity.

This starter has scored a mean of 4.2 out of 5 based on 471 votes.


Previous Day | This starter is for 23 May | Next Day

 

Answers

Show Answer

Click the button above to see all of the triangles in the diagram.

There are:

A total of 37 triangles

There is a printable worksheet to go with this activity.

Worksheet

Other shape counting starters:

How Many Squares 1? | How Many Squares 2?
How Many Triangles 1? | How Many Triangles 2? | How Many Triangles 3?
How Many Rectangles? | Rectangles Investigation | Icosahedron | Mystic Rose



Your access to the majority of the Transum resources continues to be free but you can help support the continued growth of the website by doing your Amazon shopping using the links on this page. Below is an Amazon search box and some items chosen and recommended by Transum Mathematics to get you started.

Have you read Craig's book yet?

Craig Barton must surely be the voice of Mathematics teachers in the UK. His wonderful podcasts interviewing the industry experts have culminated in this wonderful book. As Craig says: "I genuinely believe I have never taught mathematics better, and my students have never learned more. I just wish I had known all of this twelve years ago..." more...

"How I wish I’d taught maths' is an extraordinary and important book. Part guide to research, part memoir, part survival handbook, it’s a wonderfully accessible guide to the latest research on teaching mathematics, presented in a disarmingly honest and readable way. I know of no other book that presents as much usable research evidence on the dos and don’ts of mathematics teaching in such a clear and practical way. No matter how long you have been doing it, if you teach mathematics—from primary school to university—this book is for you." Dylan Wiliam, Emeritus Professor of Educational Assessment, UCL.

The Craig Barton Book

Graphic Display Calculator

This handheld device and companion software are designed to generate opportunities for classroom exploration and to promote greater understanding of core concepts in the mathematics and science classroom. TI-Nspire technology has been developed through sound classroom research which shows that "linked multiple representation are crucial in development of conceptual understanding and it is feasible only through use of a technology such as TI-Nspire, which provides simultaneous, dynamically linked representations of graphs, equations, data, and verbal explanations, such that a change in one representation is immediately reflected in the others.

For the young people in your life it is a great investment. Bought as a gift for a special occasion but useful for many years to come as the young person turns into an A-level candidate then works their way through university. more...

iPad Air

The analytics show that more and more people are accessing Transum Mathematics via an iPad as it is so portable and responsive. The iPad has so many other uses in addition to solving Transum's puzzles and challenges and it would make an excellent gift for anyone.

You have to hold iPad Air to believe it. It’s just 7.5 millimeters thin and weighs just one pound. The stunning Retina display sits inside thinner bezels, so all you see is your content. And an incredible amount of power lies inside the sleek enclosure. So you can do so much more. With so much less. more...

Before giving an iPad as a gift you could add a link to iPad Maths to the home screen.

Click the images above to see all the details of these items and to buy them online.

Online Maths Shop

Laptops In Lessons

Teacher, do your students have access to computers?
Do they have iPads or Laptops in Lessons?

Whether your students each have a TabletPC, a Surface or a Mac, this activity lends itself to eLearning (Engaged Learning).

Laptops In Lessons

Here a concise URL for a version of this page without the comments.

Transum.org/go/?Start=May23

Here is the URL which will take them to a related student activity.

Transum.org/go/?to=howmany

Student Activity

 

Curriculum Reference

See the National Curriculum page for links to related online activities and resources.


Apple

©1997-2018 WWW.TRANSUM.ORG