More or Less

Podcasts of More or Less are available via the Radio 4 website:

http://www.bbc.co.uk/podcasts/series/moreorless

Some great demonstrations of how statistics can be used to answer questions and solve problems.

Make a scratch-off card

A tutorial for making scratch-off cards (like lottery scratch cards):

http://artmind-etcetera.blogspot.co.uk/2009/05/how-to-make-scratch-off-lottery-tickets.html

Would be fab for a treasure hunt or for generating interest at the beginning of an activity...

Secret function: what's my rule?

This is based on a UK Mathematics Trust activity from the Team Maths Challenge.

Draw an input/output table on the board. Choose a function, but don't disclose it!

Fill in several non-consecutive 'input' numbers in the table. For one or two, write down the corresponding output (using your secret function).

Ask pupils for the output numbers, one input at a time. They should not disclose the rule. If they are correct, write it down and move on to the next input. If they get it wrong, ask the next student to have a go.

After several correct numbers, ask for the secret rule. 

Transformation golf

A favourite of our maths department!

http://www.mathsonline.co.uk/freesite_tour/gamesroom/transform/golftrans.html

Dubious proofs, part one

Let

x = y

Then

x² = xy

Subtract y²:

x² - y² = xy - y²

Factorise:

(x + y)(x - y) = x(x - y)

A bit of cancelling gives us

x + y = x

Let x = y = 1, so

1 + 1 = 1

Convinced?

Random name picker

From Classtools, this nifty device allows you to input a class list and then choose a name at random.

http://www.classtools.net/education-games-php/fruit_machine

1089

Via Cut-The-Knot, a magic trick from David Acheson:

http://www.cut-the-knot.org/Curriculum/Arithmetic/S1089.shtml

• Take a three digit number (e.g. 602).
• Reverse it to get another three digit number: 206.
• Subtract the smaller from the larger: 602 - 206 = 396.
• Reverse this number, and add it to the answer obtained: 693 + 396 = 1089.
• Now try with another three digit number. What do you notice?

and a couple of follow-up questions:

• Can you explain it?
• Are there any numbers for which it doesn't work? Why not?