On their break, Rocket studies the station's bus timetable. "Hey, this is a feature table too!"
Each row is a stop. Each column is a time. Raven reads it and says, "So the next bus reaches the dome at 3:40."
"You reasoned from a representation," Nova says, circling the poster. "The table stored it, and you worked it out."
Raven points to a closed stop on the map. "But the timetable does not show that. A representation can go out of date."
Rocket nods slowly. "So Sky Sorter is only as good as its table."
People use representations every day: maps, timetables, recipes and score charts.
Each one stores some facts and leaves others out.
We reason with them to get new answers, like which route is shortest.
Computers do something similar with data structures, but they do not think the way a human does.
| Representation | What it stores | What you can reason out |
|---|---|---|
| A bus timetable | Stops and times | When to leave home |
| A map | Places and roads | The shortest route |
| A team score chart | Points for each game | Which team is ahead |
| The Sky Sorter table | Brightness, size and streak | A label for each snapshot |
| Week review | True or false? |
|---|---|
| A feature table is a data structure. | ? |
| Reasoning derives new information from what is already known. | ? |
| A decision tree can be written as a flowchart or as pseudocode. | ? |
| In version 1, the brightness test comes first. | ? |
| Sky Sorter understands the night sky the way an astronomer does. | ? |
Version 1 got card E wrong. Next week the crew asks a big question.
Should people keep writing rules by hand, or can the sorter learn its rules from examples?
Superb week, explorer! Tomorrow your family builds a decision tree together.