Final answer:
Jeremiah should start by researching existing fair apps to understand the user's needs and define the features his app will need before designing and developing it.
Step-by-step explanation:
The best first step for Jeremiah to take in developing an app for the summer fair would be to research existing fair apps and analyze their features. This initial research provides a foundation of what is currently available and what features are beneficial or popular. It also helps in identifying the gaps and opportunities for improvements.
This step aligns with the first stage of the design thinking process: empathize, which involves understanding the users' needs and the problem at hand. Once this research has been conducted, Jeremiah can then apply his findings to define requirements and constraints, generate ideas, evaluate potential solutions according to the requirements, and then proceed to design the user interface, create a database, and finally write the code for the communication features.