# 246. ChrisMaths Cheer

Hey … it’s that time of year again! Baubles and cheesy jumpers are creeping into the most mundane of places. How about a more mathematical festive season?

Image credit: http://technabob.com/blog/

Here is a round up of the Sandpit’s Christmas resources:

Twelve Days of ChrisMaths

# 243. Messy Means

I have recently been teaching lower ability Year 9 students how to calculate the mean from grouped and ungrouped data tables. I didn’t want to teach them a method to learn by rote, so I used a more investigative approach.

Image Credit: http://www.thisismykea.com/designs/mr-messy

Grouped Frequency tables discussion

I started with a table with all the working shown, but some information blacked out. Each group had an A3 version and they filled in what was missing.

The second table had more information covered up. After a discussion the groups decided there wasn’t enough information and they would have to guess what the missing numbers were.

The third table had minimal information. Each group used their own method to find the missing values. Some chose the largest value in the range, some guessed what the results could have been in each group and one group decided to calculate two means – one using the largest value and one using the smallest.

We collected our results together on the board and discussed their accuracy. The class decided to use the middle of each range to calculate the estimated mean. They had gone from no understanding of estimated mean to formulating their own method.

We followed this up a Splitting the Steps estimated mean worksheet that I wrote after seeing Bruno Reddy’s presentation after #MathsConf2014 (Mr Reddy’s blog).

# 231. Fish Shop Maths

I’ve been using this idea since I first started teaching and I’ve finally got around to typing it up!

Image Credit:http://coachandhorsesn16.com/eat/fish-n-chips/

I introduce order of operations by creating an imaginary Chip Shop. I usually read out orders and get the students to write down what they think they are on whiteboards. Note that when you read out the orders, the punctuation doesn’t give any hints.

• ‘Two fish and three chips’ – 2 fish & 3 portions of chips
• ‘Fish and chips twice’ – 2 fish & 2 portions of chips or 1 fish & 2 portions of chips
• ‘Five sausage and chips’ – 5 sausages & 5 portions of chips or 5 sausages & 1 portion of chips

This activity always prompts a ‘discussion’ as to who is correct. The misconception of what an order could mean links nicely with the misconception when working out 2 + 3 x 4. You could also adapt the idea for writing algebraic expressions.

Fish Shop BIDMAS (pptx)

Fish Shop BIDMAS (ppt)

Fish Shop BIDMAS (ppsx)

# 89. What’s going on?

A few days ago I mentioned on Twitter that I was up to something. That something was expanding the Maths Sandpit from readable blog to downloadable resource. There are now resources available on YouTube and TES resources.

Over the next couple of months I am going to go back over my blog posts and add some related resources to the appropriate sites. I hope you find them useful.

The activity SimCon now has resources on the Tes Resources site.

# 86. Snapdragon & Resources

I’ve just started sharing resources on the Times Educational Supplement (TES) website.

The first resource is a typed up version of the Trigonometry Snapdragon.

I’ve omitted the diagrams so you can have a discussion about what the different situations look like.

Update: I am hosting my own resources now so you can download the snapdragon here: Trigonometry snapdragon v2