Your job for this discussion board is to choose a developmental period and design an app that would apply to them. It could be a game, a self-help app, a parenting resource app, etc.
For your discussion thread:
Describe your app. What is the purpose?
How does it work?
Identify the target audience for your app (i.e., who you would want to buy/download it).
Discuss key developmental markers or characteristics for that age group (include textbook citations).
Discuss the key developmental period or elements that this app will address, using citations from your textbook to support the need for your app.