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 adfree access to the Transum website for you and your pupils.
Topics: Starter  Combinations  Problem Solving  Shape
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:
This starter has scored a mean of 3.7 out of 5 based on 785 votes.
Previous Day  This starter is for 23 May  Next Day
Click the button above to see all of the triangles in the diagram.
There are:
There is a printable worksheet to go with this activity.
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.
Hello WorldYou are buying a (driverless) car. One vehicle is programmed to save as many lives as possible in a collision. Another promises to prioritize the lives of its passengers. Which do you choose? Welcome to the age of the algorithm, the story of a nottoodistant future where machines rule supreme, making important decisions – in healthcare, transport, finance, security, what we watch, where we go even who we send to prison. So how much should we rely on them? What kind of future do we want? Hannah Fry takes us on a tour of the good, the bad and the downright ugly of the algorithms that surround us. In Hello World she lifts the lid on their inner workings, demonstrates their power, exposes their limitations, and examines whether they really are an improvement on the humans they are replacing. more... 
Teacher, do your students have
access to computers? 

Here a concise URL for a version of this page without the comments.
Here is the URL which will take them to a related student activity.
See the National Curriculum page for links to related online activities and resources.