Trial and improvement [ A3.1 Core Starter] Choose five whole numbers which are not square numbers Estimate the square root of each of your chosen numbers Find the difference between of each of your estimate square roots and the square roots calculated on your calculator Add these five differences together – this gives the total error Compare your total error with the table below. Total error Performance 0 to 0.49 Excellent 0.5 to 0.9 Very good 1 to 1.9 Good 2 to 2.9 Fair 3 or above You need a bit more practice Preamble This could be a wipe board activity – it is assumed that pupils are able to recall the square and cube roots of square and cube numbers, so some might need to “get up to speed”. A post-activity discussion strategies is useful, including one relating to the fairness or otherwise of the performance rating system. Possible content Estimating square and cube roots based on pupils previous knowledge of squares and cubes of integers. Simple decimal calculations. Resources Possibly a calculator to check square roots (total error calculation probably best as a non-calculator activity). Solution/Notes Pupils own estimations. Original Material © Cambridge University Press 2010 Original Material © Cambridge University Press 2010