Skip to main content

Prime Factor Decomposition



I have stopped using a Prime factor tree when teaching Prime Factor Decomposition and so should you!

Here's why:

1. Students mix up Frequency trees and Prime Factor trees. 


2. Students don't always realise that the prime numbers are the 'building blocks' of the number and they just need to complete the tree to get the mark.


3. Incorrectly writing their final answer.



What I now do:
It still looks very similar but I have a big focus on rewriting the original number each time and using a line for each step of their workings.


For some students I have used little arrows to show which numbers need to be split further and underlined the prime numbers so they can more clearly identify what their next step is.

I explicitly teach about using the numbers to 'go backwards' and find other factors e.g. 3 x 2 x 2 = 12 which is a factor of 72.

I show students how no matter the starting point, we still end up with the same building blocks e.g. if we started with 2 x 36 we would still end up with the same answer.

I recently taught my Year 7 class this method and found a lot less of the 'classic' misconceptions coming up which gave us more time to explore the topic to much greater depth.



Labels:

Popular posts from this blog

Literacy in Maths

I'm a Maths teacher, I teach numbers. Why is Literacy so important for me? Well….here's why: "Literacy is fundamental for success in school and later life. Students who cannot read, write and communicate effectively are highly unlikely to access the challenging academic curriculum in secondary school and are more likely to have poor educational outcomes across all subjects." (Link 3)  Unfortunately there are a lot of Maths teachers who believe (wrongly) that literacy is a thing that the English department do. They see it as a tick box for observations. Rather than being an essential component of students being able to learn maths.  -  So what does it look like in Maths? Answer the question: Blindle 4x + 6 Are you able to do it?  This is the challenge a lot of students face in Mathematics. Subject specific vocabulary can seem really confusing to a lot of students. Understanding what a keyword is asking of students is often the hardest part of a question and can hold s...
Read more

📝 Weekly Report #33

This week I listened to a really good podcast episode from Greg McKeown called Where am I wrong? In it he talks about a really effective method to have deeper discussions on what is important.  Write down/say the 3-5 issues/priorities you think there are as well as the cost/consequence of them. Then just simply ask where am I wrong? It starts the conversation off with the other person talking and getting their points across. You can then get that shared understanding about what needs to be done and why.  It got me thinking about other areas this could be useful for e.g. dealing with conflicts, leading departments/teams, pitching a new initiative. I am going to start doing this in some of these scenarios as I think we can have more productive conversations from it.  Have a listen to the episode here .  🔊 Listen: Alan Stein Jr on the Modern Wisdom podcast discussing high performance and overcoming stress. He talks about thinking like an athlete with your work and impr...
Read more

England v Wales: Who teaches Maths better?

England V Wales: Who teaches Maths better? Times are changing in Wales, there is a new Curriculum focus and in Maths there are 5 proficiencies that the government want to see. Here's my take as a new HOD crossing the border from England. The Welsh government have overhauled the curriculum and not just in Maths. They have identified key statements of what matters and laid out principles for progressing in each subject.  Maths in every country is the same though surely.... Well yes... we still focus on Number, Algebra, Geometry and Statistics. But also no....in Wales it is mandatory to use their 5 proficiencies to progress students in Maths. This isn't an explicit thing in England. The 5 proficiencies are: conceptual understanding, fluency, logical thinking, strategic competence and communication with symbols Lots of big words. But if you dive deeper into the detail that the Welsh government provides on each of them it is no different to what the NCETM in England recommend with t...
Read more