# Trial and Improvement

# 'Mental Maths Estimates leading to Excel Maths Precision'

Using the presentation below, remind yourself what squared, square root, cube and cube root means and use your knowledge of perfect squares and cubes to help you estimate other square and cube roots.

Once you've sharpened up your mental maths skills, it's time to combine them with Excel to move towards increasingly accurate solutions to squared and cubed equations. Use an estimate and your knowledge of perfect squares and cubes to get you started, then let excel do the manual work leaving you free to reason what the next best trial (educated guess!) will be. See if you can find the solution in as few attempts as possible! See video below for an overview of the activity.

### Resources

This is a simple presentation to use as a mental introduction to Trial and improvement methods. Students can work on paper or mini-whiteboards, in teams, pairs or individually in competition format or not, to solve the problems set: Squares, Roots and Cubes.

Now it's time to hone those estimations down to 1 d.p., 2 d.p. and 3 d.p. accuracy! Trial and Improvement

### Description

- Use the "Squares, Roots and Cubes" questions as a reminder of how to square, square root, cube and cube root. Students can work on paper or mini-whiteboards, in teams, pairs or individually in competition format or not, to solve the problems set.
- Student's use the Excel worksheet to hone their estimate to within 1d.p.either side of the target number. Students can only access cells to enter their estimates and solutions, the other cells containing formulae etc. are locked so as to avoid accidental deletion.
- Demonstrate, using the Excel worksheet, the difference between an answer to 1d.p., 2d.p. and 3 d.p.
- On the final sheet, students attempt to find answers to different degrees of accuracy. The same questions are available on an editable and non-editable sheet. For extension students, the editable sheet allows them to insert a column, create IF statements to test their estimates or to create their own questions to exchange with a partner etc.

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