See also: Matching topics (16) Matching titles (121)
Back Fitter
Stage: 4 Challenge Level: 
10 graphs of experimental data are given. Can you use a spreadsheet to find algebraic graphs which match them closely, and thus discover the formulae most likely to govern the underlying processes?
2009 Challenge
Stage: 3, 4 and 5 Challenge Level:
We asked what was the most interesting fact that you can find out about the number 2009. See the solutions that were submitted.
Partly Circles
Stage: 4 Challenge Level:
What is the same and what is different about these circle questions? What connections can you make?
Understanding Hypotheses
Stage: 3, 4 and 5
This article explores the process of making and testing hypotheses.
Data Collection Tool
Stage: 3 and 4 Challenge Level:
An interactivity that enables you collect data from an experiment with true/false outcomes.
Adding and Subtracting Positive and Negative Numbers
Stage: 3 and 4
How can we help students make sense of addition and subtraction of negative numbers?
Napier's Location Arithmetic
Stage: 4 Challenge Level:
Have you seen this way of doing multiplication ?
Interactive Number Patterns
Stage: 4 Challenge Level:
How good are you at finding the formula for a number pattern ?
Spotting the Loophole
Stage: 4 Challenge Level:
A visualisation problem in which you search for vectors which sum to zero from a jumble of arrows. Will your eyes be quicker than algebra?
Difference Sudoku
Stage: 3 and 4 Challenge Level:
Use the differences to find the solution to this Sudoku.
Walking Around a Cube
Stage: 3 and 4 Challenge Level:
Find the length along the shortest path passing through certain points on the cube.
Matchless
Stage: 3 and 4 Challenge Level:
There is a particular value of x, and a value of y to go with it, which make all five expressions equal in value, can you find that x, y pair ?
Sine and Cosine
Stage: 4 Challenge Level:
The sine of an angle is equal to the cosine of its complement. Can you explain why and does this rule extend beyond angles of 90 degrees?
Dating Made Easier
Stage: 4 Challenge Level:
If a sum invested gains 10% each year how long before it has doubled its value?
Nicely Similar
Stage: 4 Challenge Level:
If the hypotenuse (base) length is 100cm and if an extra line splits the base into 36cm and 64cm parts, what were the side lengths for the original right-angled triangle?
Integrated Product Sudoku
Stage: 3 and 4 Challenge Level:
This Sudoku puzzle can be solved with the help of small clue-numbers on the border lines between pairs of neighbouring squares of the grid.
Integrated Sums Sudoku
Stage: 3 and 4 Challenge Level:
The puzzle can be solved with the help of small clue-numbers which are either placed on the border lines between selected pairs of neighbouring squares of the grid or placed after slash marks on. . . .
Spaces for Exploration
Stage: 3 and 4
Alf Coles writes about how he tries to create 'spaces for exploration' for the students in his classrooms.
Equal Temperament
Stage: 4 Challenge Level:
The scale on a piano does something clever : the ratio (interval) between any adjacent points on the scale is equal. If you play any note, twelve points higher will be exactly an octave on.
Intersections
Stage: 4 and 5 Challenge Level:
Change one equation in this pair of simultaneous equations very slightly and there is a big change in the solution. Why?
Odd Stones
Stage: 4 Challenge Level:
On a "move" a stone is removed from two of the circles and placed in the third circle. Here are five of the ways that 27 stones could be distributed.
Intersection Sums Sudoku
Stage: 2, 3 and 4 Challenge Level:
A Sudoku with clues given as sums of entries.
Diagonal Sums Sudoku
Stage: 2, 3 and 4 Challenge Level:
Solve this Sudoku puzzle whose clues are in the form of sums of the numbers which should appear in diagonal opposite cells.
Trapezium Four
Stage: 4 Challenge Level:
The diagonals of a trapezium divide it into four parts. Can you create a trapezium where three of those parts are equal in area?
Substitution Cipher and Frequency Analysis
Stage: 4 Challenge Level:
Investigate some text to find the frequency distribution for ordinary English and use that to help you crack the coded text below.
Product Sudoku 2
Stage: 3, 4 and 5 Challenge Level:
Given the products of diagonally opposite cells - can you complete this Sudoku?
Product Sudoku
Stage: 3, 4 and 5 Challenge Level:
The clues for this Sudoku are the product of the numbers in adjacent squares.
Motion Capture
Stage: 3 and 4 Challenge Level:
Explore displacement/time and velocity/time graphs with this mouse motion sensor.
Steady Free Fall
Stage: 4 Challenge Level:
Can you adjust the curve so the bead drops with near constant vertical velocity?
A Change in Code
Stage: 4 Challenge Level:
There are two sets of numbers. The second is the result of the first after an increase by a constant percentage. How can you find that percentage if one set of numbers is in code?
Orbiting Billiard Balls
Stage: 4 Challenge Level:
What angle is needed for a ball to do a circuit of the billiard table and then pass through its original position?
Swings and Roundabouts
Stage: 4 Challenge Level:
If you were to set the X weight to 2 what do you think the angle might be?
Figure of Eight
Stage: 4 Challenge Level:
On a nine-point pegboard a band is stretched over 4 pegs in a "figure of 8" arrangement. How many different "figure of 8" arrangements can be made ?
Right Angles
Stage: 3 and 4 Challenge Level:
Can you make a right-angled triangle on this peg-board by joining up three points round the edge?
High Jumping
Stage: 4
How high can a high jumper jump? How can a high jumper jump higher without jumping higher? Read on...
Where to Land
Stage: 4 Challenge Level:
Chris is enjoying a swim but needs to get back for lunch. If she can swim at 3 m/s and run at 7m/sec, how far along the bank should she land in order to get back as quickly as possible?
Square It
Stage: 1, 2, 3 and 4 Challenge Level:
Players take it in turns to choose a dot on the grid. The winner is the first to have four dots that can be joined to form a square.
Salinon
Stage: 4 Challenge Level:
This shape comprises four semi-circles. What is the relationship between the area of the shaded region and the area of the circle on AB as diameter?
The Spider and the Fly
Stage: 4 Challenge Level:
A spider is sitting in the middle of one of the smallest walls in a room and a fly is resting beside the window. What is the shortest distance the spider would have to crawl to catch the fly?
Leonardo's Problem
Stage: 4 and 5 Challenge Level:
A, B & C own a half, a third and a sixth of a coin collection. Each grab some coins, return some, then share equally what they had put back, finishing with their own share. How rich are they?
Enriching Networks, Inspiring Teachers
Stage: 3 and 4
Here are examples of how two schools set about the task of ensuring that problem solving was an integral part of their curriculum.
Ancient Astronomical Terms
Stage: 3, 4 and 5
Some explanations of basic terms and some phenomena discovered by ancient astronomers
History of Trigonometry Part 2
Stage: 3, 4 and 5
The second of three articles on the History of Trigonometry.
The History of Trigonometry- Part 1
Stage: 2, 3, 4 and 5
The first of three articles on the History of Trigonometry. This takes us from the Egyptians to early work on trigonometry in China.
Power Quady
Stage: 4 Challenge Level:
Find all real solutions of the equation (x^2-7x+11)^(x^2-11x+30) = 1.
Turning the Place Over
Stage: 3, 4 and 5 Challenge Level:
As part of Liverpool08 European Capital of Culture there were a huge number of events and displays. One of the art installations was called "Turning the Place Over". Can you find our how it works?
Assessing Pupil Progress (APP) and NRICH Resources
Stage: 1, 2, 3, 4 and 5
In this article Jenny talks about Assessing Pupils' Progress and the use of NRICH problems.
Investigating Solids with Face-transitivity
Stage: 4 and 5
In this article, we look at solids constructed using symmetries of their faces.
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