### Right Time

At the time of writing the hour and minute hands of my clock are at right angles. How long will it be before they are at right angles again?

### Kite

Derive a formula for finding the area of any kite.

### The Pi Are Square

A circle with the radius of 2.2 centimetres is drawn touching the sides of a square. What area of the square is NOT covered by the circle?

# All in a Jumble

##### Stage: 3 Challenge Level:

My measurements have got all jumbled up!

Drag the entries in the table up and down until all the measurements match up sensibly. For some items there are a few numbers which would be valid. You have to juggle them to find a combination where every measurement is valid.

This page will be different every time you load it or refresh it - so if you have unscrambled one set of measurements, you can try a new set. See if you can do it with fewer uses of the 'score' button!

Small version for getting used to the idea:

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Score - each item gets a maximum of three marks:
• correct type of unit
• within 20% of our estimate
• within 1% of our estimate
On the large version, a good strategy is to drag finished items to the top of the list, so they won't get mixed around by your later work. If there are a few similar numerical values in your list, you might need to swap pairs over to get the last few marks.

Large version for a real workout!

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The following sets of cards are available if you want students to work away from the computer. They will of course lose the facility to check their results online.
Card sort 1
Card sort 2
Card sort 3
Alternatively, you could right click over a table and select the option to print.