Final answer:
The best devices for the geocache treasure hunt, given a $650 budget, are affordable smartphones which provide necessary communication capabilities like messaging and GPS. Two devices can be purchased within the budget, allowing for effective coordination between students at different locations.
Step-by-step explanation:
In choosing the right mobile devices for student communication during a geocache treasure hunt with a budget of $650, we must consider various factors. The primary needs are reliability, the ability to send and receive messages, and affordability. Given these needs, smartphones are likely the best option for both students, whether near the coffee shop or two miles from the school.
For proximal communication, basic smartphones offer the needed functionality. They can access GPS for navigation, run geocaching or communication apps, and cost around $200-$300 each. Buying two devices would total $400-$600, leaving some funds for app purchases or additional data plans if needed.
When opting for smartphones, trade-offs include choosing less expensive models that may lack premium features such as high-end cameras or large storage space. Yet, these features are not requisites for our purpose. Therefore, sacrificing some luxury features enables us to stay within budget and fulfill the communication needs effectively.