The spreadsheet is a great example. The core mental model is extremely simple: it's the same as a paper spreadsheet but you can put calculations (formulas) in a

The spreadsheet is a great example. The core mental model is extremely simple: it's the same as a paper spreadsheet but you can put calculations (formulas) in a cell. That's it! That's the mental model. Once you go beyond that model, people get confused. What's a pivot table? What's the difference between $A1 and A$1? Why is my date showing up as a number? But it works because 80% of the people only need to know about the basic mental model. If you try to reduce email, notes, meetings into a single mental model, then you're back to the puzzle problem and people have to solve it to do even the simplest thing. You may or may not remember Lotus Improv, which was effectively a reinvention of the spreadsheet. In Improv, the core mental model was the pivot table, which allowed you to do some amazing things (e.g., "add up the sales for each quarter by product type"). But even the simplest things required people to understand the core concepts of a pivot table (columns, categories, rows, etc.). Tech people loved it. Normal people, not so much.