This is the forth lesson in the ‘App Inventor’ scheme of work. This lesson combines practical and theory to teach the “representing sound” concepts covered in the Computer Science 9-1 GCSE specifications, (including; sample rate, sample resolution & calculating audio file size.) All lessons within the scheme are targetted at KS3/KS4. Each slide includes detailed notes to support teacher understanding and have been based on a lesson plan structure. There is no prior knowledge required from the class teacher as the guides provided are step-by-step & all code is catered for in the documentation provided. For this lesson a video tutorial is available to support learners with the design of their app. The lesson includes a minimum 45 minute assessment (electronic & paper based included) with mark scheme both of which are custom made, this will truly test learner’s understanding. Using the ‘App Inventor’ emulator or a mobile device with the 'MIT App Inventor app’ installed will allow learners to practically use the apps they build. The app can be downloaded freely from the ‘Google Play’ store.