Introduction: Error Correction Exercises-How do the Exercises Work?, What does this Approach Offer?, A Rationale for this Approach, Errors and Misconceptions, How to Use the Exercises, Writing Frames, Further Outcomes of the Trials, Appendix 1.1: The Place Value of Gattegno Chart, Appendix 1.2: Place Value Chart, Appendix 1.3: Decimal Number Line; Using the Exercises; The Exercises-Numbers and the Number system, Rounding Numbers, Decimals, Calculation, Multiplying and Dividing by 10 and 100, Solving Numerical Problems, Interpreting Calculator displays, Coordinates, Using Protractors and Rulers, Reading Scales; Appendix A: Briefing Sheet; Appendix B: Writing Frame; Appendix C: Writing Frame; Bibliography