Which assumption should you test first in a side project?
Find a condition that would force you to rethink the idea if it proved false. Design a small observation around it before building the whole product. Your first output is an assumption record.
Separate the conditions
A community-events digest might assume that information is difficult to find and that people want a weekly email. Those are different questions. State the critical condition and what observation would change your mind; expecting people to like an idea is insufficient.
Match the material to the question
To explore discovery difficulties, invite a willing person to demonstrate their recent search. To explore readability, make a clearly labeled sample. Praise for that sample does not establish subscription demand. Record behavior and the conditions you did not test.
A worksheet you can use
Idea: __. Critical assumption: __. Consequence if false: __. Observable signal: __. Material: __. Unknown: __.
What if the main assumption is difficult to test?
Observe one relevant part and preserve the remaining uncertainty rather than substituting an easy but unrelated metric.
Evidence and scope
Small exploratory tests cannot estimate market size, income or success probability. This worksheet is editorial.
IDEO.org discusses iterative prototyping. WKND examples are editorial, not endorsed. IDEO.org Design Kit — Rapid Prototyping
Sources and further reading
This collection in Chinese and English · Life possibilities library