Percentages out of 100

Show how to scale up simple proportions like 13 out of 20 to make them into percentages. Based on the results of a survey on pet ownership. Use pie charts to visualise the results. Understand percentages as 'number of parts per hundred'.  
  
This colourful powerpoint presentation and accompanying worksheet allow you to revise/teach different ideas using an easy to understand situation and could be the basis for further work on data collection.