How Many Triangles?A self marking step by step approach to calculating the number of triangles in a design. 
The first few questions are about counting the number of triangles in this design:
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
InstructionsTry your best to answer the questions above. Type your answers into the boxes provided leaving no spaces. As you work through the exercise regularly click the "check" button. If you have any wrong answers, do your best to do corrections but if there is anything you don't understand, please ask your teacher for help. When you have got all of the questions correct you may want to print out this page and paste it into your exercise book. If you keep your work in an ePortfolio you could take a screen shot of your answers and paste that into your Maths file. 



Transum.orgThis web site contains over a thousand free mathematical activities for teachers and pupils. Click here to go to the main page which links to all of the resources available. Please contact me if you have any suggestions or questions. 
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AnswersThere are answers to this exercise but they are available in this space to teachers, tutors and parents who have logged in to their Transum subscription on this computer. A Transum subscription unlocks the answers to the online exercises, quizzes and puzzles. It also provides the teacher with access to quality external links on each of the Transum Topic pages and the facility to add to the collection themselves. Subscribers can manage class lists, lesson plans and assessment data in the Class Admin application and have access to reports of the Transum Trophies earned by class members. If you would like to enjoy adfree access to the thousands of Transum resources, receive our monthly newsletter, unlock the printable worksheets and see our Maths Lesson Finishers then sign up for a subscription now: Subscribe 

Go MathsLearning and understanding Mathematics, at every level, requires learner engagement. Mathematics is not a spectator sport. Sometimes traditional teaching fails to actively involve students. One way to address the problem is through the use of interactive activities and this web site provides many of those. The Go Maths page is an alphabetical list of free activities designed for students in Secondary/High school. Maths MapAre you looking for something specific? An exercise to supplement the topic you are studying at school at the moment perhaps. Navigate using our Maths Map to find exercises, puzzles and Maths lesson starters grouped by topic.  
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If you found this activity useful don't forget to record it in your scheme of work or learning management system. The short URL, ready to be copied and pasted, is as follows: 
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Do you have any comments? It is always useful to receive feedback and helps make this free resource even more useful for those learning Mathematics anywhere in the world. Click here to enter your comments. 
© Transum Mathematics :: This activity can be found online at:
www.transum.org/software/SW/Starter_of_the_day/Students/HowMany.asp
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This self marking quiz takes you through the stages of a systematic approach to solving the 'How Many Triangles?' question.
You might find it helpful to print out this page containing a number of copies of the designs so that you can colour in the triangles you find.
More Puzzles including lesson Starters, visual aids and investigations.
Answers to this exercise are available lower down this page when you are logged in to your Transum account. If you donâ€™t yet have a Transum subscription one can be very quickly set up if you are a teacher, tutor or parent.
See the National Curriculum page for links to related online activities and resources.
Transum,
Friday, January 23, 2015
"This activity is all about breaking down a big difficult task into smaller, more achievable tasks. Not everyone can come up with an effective strategy for themselves so a structured guide like this exercise is a way of helping them learn. There are many other activities related to the process of counting strategies on the Combinations and Permutations section of this website."
Guillaume, France
Sunday, September 18, 2016
"Hi !
On the page "How many triangles", at question #2:
"Next count the number of triangles made from two pieces like this green one:" Your expected answer is 12 but I can only find 6 of them... Is there an error?
Best regards.
[Transum: Thank you Guillaume for your comment. The other green triangles are equilateral triangles so are not similar in shape to the example given. On reflection the wording of the question possibly suggested that it was shapes similar to the example that you should count and indeed there are only six of them. I have changed the wording of the question to make it more clear that it is all twopiece triangles that should be counted.]"