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# What Makes A Good Resource - If I Know This I Also Know

This page has been archived. The content was correct at the time of original publication, but is no longer updated.
Created on 08 September 2009 by ncetm_administrator
Updated on 03 September 2010 by ncetm_administrator

# If I Know This I Also Know

Resource description:
This is an Excel spreadsheet which is put up at the front of the class.

Teacher comment:
In my teaching I have always found that students can easily answer questions like 7×4, provided they know their times tables, but find it a lot harder for when they are asked to answer something like 40×0.7. I developed this to show students that once they learn one little bit of knowledge it opens up several doors of other bits of information to access.

What I did:
I put this spreadsheet up on the projector and ask students to copy it down in to their books and work out the answers. Often some students will give up before they have started the activity because they see something like 120×1700 and decide that they can’t do it because the numbers are too big and they fail to see the connection between that and 12×17=204. I try not to give them the solution to do this but ask questions like, “What’s happened to the 12, so what should happen to the answer?” I also have a place value chart handy, so that students can use it for multiplying or dividing by powers of 10.

Once students grow in confidence and ability in this activity I will simply write something like 13×11=143 in the middle of the board and ask them to write what else they know. I encourage them to make it as hard and as challenging as possible. Some students take this to the extreme and have some fantastic ideas.

Reflection:
By doing this students start to see the links between different calculations and how doing a simple calculation can help you solve more complex ideas. When students are explaining how they got from 12×17=204 to 170×12=2040 they talk about adding one zero to 17, so therefore adding one zero to 204. Personally I would discourage this and try to get students to describe this as moving numbers one place to the left or multiplying by 10. I’ve used this activity to start lessons with different abilities and age groups, as it is very easy to differentiate because of the openness of the extension task.

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