60Lower Secondary big button pagehttp://nrich.maths.org/secondary-loweren 2012 http://nrich.maths.org/public/terms.phpExploring Mathematics on Dotty Gridshttp://nrich.maths.org/10792Sat, 01 Feb 2014 00:00:01 +0000Estimating TimeHow well can you estimate 10 seconds? Investigate with our timing tool.http://nrich.maths.org/10629Sun, 01 Dec 2013 00:00:01 +0000Picturing the WorldHow can we make sense of national and global statistics involving very large numbers?http://nrich.maths.org/10464Tue, 01 Oct 2013 00:00:01 +0100Making Sense of Positives and NegativesThis article suggests some ways of making sense of calculations involving positive and negative numbers.http://nrich.maths.org/9958Wed, 01 May 2013 00:00:01 +0100Strange Bank Account (part 2)Investigate different ways of making £5 at Charlie's bank.http://nrich.maths.org/9943Wed, 01 May 2013 00:00:01 +0100Up, Down, Flying AroundPlay this game to learn about adding and subtracting positive and negative numbershttp://nrich.maths.org/9941Wed, 01 May 2013 00:00:01 +0100Strange Bank AccountImagine a very strange bank account where you are only allowed to do two things...http://nrich.maths.org/9923Mon, 01 Apr 2013 00:00:01 +0100Perimeter PossibilitiesI'm thinking of a rectangle with an area of 24. What could its perimeter be?http://nrich.maths.org/9691Sat, 01 Dec 2012 00:00:01 +0000Constructing TrianglesGenerate three random numbers to determine the side lengths of a triangle. What triangles can you draw?http://nrich.maths.org/8098Wed, 01 Aug 2012 00:00:01 +0100Changing Areas, Changing Perimeters
How can you change the area of a shape but keep its perimeter the same? How can you change the perimeter but keep the area the same?
http://nrich.maths.org/7534Sun, 01 May 2011 00:00:01 +0100Who's the Best?Which countries have the most naturally athletic populations?http://nrich.maths.org/7367Wed, 01 Jun 2011 00:00:01 +0100Always a Multiple?Think of a two digit number, reverse the digits, and add the numbers together. Something special happens...http://nrich.maths.org/7208Tue, 01 May 2012 00:00:01 +0100Dicey OperationsWho said that adding, subtracting, multiplying and dividing
couldn't be fun?http://nrich.maths.org/6606Tue, 01 Feb 2011 00:00:01 +0000Curvy AreasHave a go at creating these images based on circles. What do you notice about the areas of the different sections?http://nrich.maths.org/6468Tue, 01 Feb 2011 00:00:01 +0000Power Mad!Powers of numbers behave in surprising ways. Take a look at some of these and try to explain why they are true.http://nrich.maths.org/6401Tue, 01 Feb 2011 00:00:01 +0000Reaction TimerThis problem offers you two ways to test reactions - use them to
investigate your ideas about speeds of reaction.http://nrich.maths.org/6044Tue, 01 Feb 2011 00:00:01 +0000WeightsDifferent combinations of the weights available allow you to make different totals. Which totals can you make?http://nrich.maths.org/5958Tue, 01 Feb 2011 00:00:01 +0000Playing Connect ThreeIn this game the winner is the first to complete a row of three.
Are some squares easier to land on than others?http://nrich.maths.org/5864Tue, 01 Feb 2011 00:00:01 +0000Difference SudokuUse the differences to find the solution to this Sudoku.http://nrich.maths.org/5798Sun, 01 Dec 2013 00:00:01 +0000ACE, TWO, THREE...Can you picture how to order the cards to reproduce Charlie's card trick for yourself?http://nrich.maths.org/5775Tue, 01 Feb 2011 00:00:01 +0000Method in Multiplying Madness?Watch our videos of multiplication methods that you may not have met before. Can you make sense of them?http://nrich.maths.org/5612Sat, 01 Oct 2011 00:00:01 +0100Isosceles TrianglesDraw some isosceles triangles with an area of $9$cm$^2$ and a vertex at (20,20). If all the vertices must have whole number coordinates, how many is it possible to draw?http://nrich.maths.org/2666Tue, 01 Feb 2011 00:00:01 +0000Fence ItIf you have only 40 metres of fencing available, what is the maximum area of land you can fence off?http://nrich.maths.org/2663Sat, 01 Dec 2012 00:00:01 +0000Shady SymmetryHow many different symmetrical shapes can you make by shading triangles or squares?http://nrich.maths.org/1868Tue, 01 Feb 2011 00:00:01 +0000FrogsHow many moves does it take to swap over some red and blue frogs? Do you have a method?http://nrich.maths.org/1246Tue, 01 Feb 2011 00:00:01 +00001 Step 2 StepLiam's house has a staircase with 12 steps. He can go down the steps one at a time or two at time. In how many different ways can Liam go down the 12 steps?http://nrich.maths.org/1019Tue, 01 Feb 2011 00:00:01 +0000Attractive TableclothsCharlie likes tablecloths that use as many colours as possible, but insists that his tablecloths have some symmetry. Can you work out how many colours he needs for different tablecloth designs?http://nrich.maths.org/900Wed, 01 Jun 2011 00:00:01 +0100Two and TwoHow many solutions can you find to this sum? Each of the different letters stands for a different number.http://nrich.maths.org/781Tue, 01 Feb 2011 00:00:01 +0000Pair SumsFive numbers added together in pairs produce: 0, 2, 4, 4, 6, 8, 9, 11, 13, 15 What are the five numbers?http://nrich.maths.org/481Tue, 01 Feb 2011 00:00:01 +0000