Data Lifecycle — Test Your Understanding

Answer each question thoroughly. There is no code here — only thinking. If you can't answer confidently, revisit the Why and How sections before continuing.

Section A: Identification

Question 1

A weather app shows you the current temperature for your city.

List every piece of data involved in showing that single number on your screen. For each piece, label it as Storage, Transform, or Transport. Some pieces may involve more than one.

Question 2

You take a photo on your phone, apply a filter, and post it to social media. Your friend, in another country, sees it on their phone.

Trace the data lifecycle of that photo from the moment you press the shutter button to the moment your friend sees it. Identify every stage of storage, transform, and transport.

Question 3

A thermostat in a house reads the temperature, and if it's below 68°F, turns on the heater. When the temperature reaches 72°F, it turns the heater off.

What data is involved? Where is each piece stored? What transforms occur? What transport happens?

Section B: Analysis

Question 4

A company stores customer orders in a database. Every night at midnight, a report is generated summarizing the day's sales and emailed to the management team.

Draw the full lifecycle map (table or diagram) for this process. Include data you think the description didn't mention but that must exist for the system to work.

Question 5

You are told: "The system is slow." You know the system does three things:

1. Receives data from an external API
2. Processes that data (cleans and aggregates it)
3. Saves the result to a database

Using only the data lifecycle model, list three distinct hypotheses for why it might be slow, one related to each lifecycle stage (storage, transform, transport).

Question 6

An e-commerce site has a feature: "Customers who bought this also bought..."

What data must be stored to make this feature work? What transform produces the recommendations? When does that transform happen — when the page loads, or ahead of time? What are the tradeoffs of each approach?

Section C: Design

Question 7

You are asked to design a system for a public library's book checkout process. Patrons scan their library card, scan the book, and walk out. Overdue books generate a notification after 14 days.

Produce a full lifecycle map. Include:

• All data involved (obvious and hidden)
• Every storage location
• Every transform
• Every transport
• What happens when things go wrong (book not in system, card expired, network down)

Question 8

A food delivery app needs a feature: real-time order tracking. The customer can see "Order received," "Being prepared," "Out for delivery," and "Delivered" with live updates.

Map the lifecycle of the order status specifically. Where is status stored? What triggers each status change (transform)? How does the updated status reach the customer's screen (transport)? What happens if the driver's phone loses connectivity?

Question 9

A school wants a system where teachers enter grades, students can view their own grades, and parents receive a weekly email summary.

Three different types of users interact with the same data. Map the full lifecycle showing how grade data flows differently for each user type. Identify where the data is shared and where it diverges.

Section D: Critical Thinking

Question 10

Someone proposes: "Let's just store everything in one big database table and figure out the rest later."

Using what you know about the data lifecycle, explain specifically what problems this creates. Don't just say "it's bad" — identify at least three concrete consequences and relate each one back to storage, transform, or transport.

Question 11

You mapped a system's data lifecycle and found that the same piece of data is stored in three different places (a database, a cache, and a local file).

Is this a problem? Under what circumstances would it be the right design? Under what circumstances would it be a mistake? What specific risks does it introduce?

Question 12

A feature request says: "When a user uploads a profile picture, it should appear immediately on their profile."

This sounds simple. Using lifecycle thinking, list everything that actually needs to happen between "user selects a file" and "image appears on profile page." Identify the stages that could fail and what the user would experience in each failure case.

Grading Rubric

For each question, evaluate your answer against these criteria:

If your lifecycle map is missing stages, it means you're not seeing the full picture yet. That's fine — re-read the material and try again. The goal is not to get it right the first time. The goal is to train your brain to automatically think in lifecycles.