Importance and abstraction levels
Not every piece of information matters the same. Some pieces tell you what the whole thing is about. Others only add a small fact. To rank information we use two questions.
Question 1: How important is it?
If you remove this idea, does the text still make sense? If not, it is important. A date or a small example can often be removed. The main claim cannot.
Question 2: How general is it?
An idea can be general (it covers many things) or specific (it covers one thing). "Sport" is general. "Football" is less general. "Messi's goal in 2022" is very specific. These steps from general to specific are called abstraction levels. The higher the level, the more things the idea covers.
Abstract here means "pulled away from the small details". A summary is a high level. A full report is a low level.
| Level | Example | Job |
|---|---|---|
| High (general) | Animals | Names the whole topic |
| Middle | Birds | A group inside the topic |
| Low (specific) | Sparrow | One clear example or fact |
Important does not always mean general. A very small fact (a warning on a medicine) may be the most important. So check both questions separately.
Organising in hierarchies
A hierarchy is a way of arranging things in levels, where each item has one parent above it and may have children below it. Use these steps.
- Collect all the pieces (facts, ideas, sentences).
- Find the big idea that covers everything. Write it as one short phrase.
- Make groups. Put pieces that are alike together and name each group.
- Place details under the right group. Each detail should belong to only one group.
- Check: is every item at the right level? Can each group name cover all its details?
Ways to show a hierarchy
- Outline: 1, 1.1, 1.2 or I, A, a. Good for essays and notes.
- Tree or mind map: good for seeing the whole picture.
- Headings: h1, h2, h3 in a document or a web page.
- Folders: a folder holds sub-folders and files.
Good habits
Keep each level at about 3 to 7 items so the reader is not overloaded. Keep items on one level equally general: do not put "Birds" and "Sparrow" side by side. Use clear names that tell the reader what is inside.
Try it yourself
Take 10 things from your school bag and your classroom. Write each on a small paper. Mix them up. Now do three jobs: (1) pick the big idea that covers all, (2) make 2 or 3 groups, (3) place every paper under a group. Then guess: how many levels did you need? Use the slider in the 3D to compare the summary, the outline and the full detail.
Key formulas and definitions
- Hierarchy = big idea (top) > groups (middle) > details (bottom)
- Abstraction level: higher = more general, lower = more specific
- Importance test: if removed, does the text still make sense?
- Rule: each item has one parent; items on one level are equally general
- Outline numbering: 1 > 1.1 > 1.1.1
Worked examples
1. Sort into a hierarchy: Fruits, Mango, Apple, Vegetables, Carrot, Spinach, Food.
Top: Food. Middle: Fruits and Vegetables. Bottom: Mango and Apple under Fruits; Carrot and Spinach under Vegetables. Food is the most general, the four names are the most specific.
2. A paragraph says: "Our village needs a library. Books help children learn. A library gives a quiet place. The old school room is empty." Which sentence is the top-level idea? Make an outline.
Top idea: Our village needs a library. Under it: 1. Books help children learn. 2. A library gives a quiet place. 3. The old school room is empty (a place we can use). The first sentence covers the other three, so it is the highest level.
3. A student writes the outline: Pets / Dogs / Cats / Labrador. Find the mistake and correct it.
Labrador is a kind of dog, so it is more specific than Cats, but it sits on the same level as Dogs and Cats. Fix: Pets > Dogs (> Labrador) and Pets > Cats. Items on one level must be equally general.
4. You must give a 10-second summary of a 3-page article on water saving. Which level do you use and why?
The top level (big idea) and maybe the groups. A short summary only needs the high abstraction levels; low-level details like numbers are left out.
Common mistakes
- Putting a general idea and a specific one side by side on the same level (Birds and Sparrow).
- Making too many items on one level. More than 7 is hard to remember: add a group.
- Thinking "important" and "general" mean the same. A small warning can be very important.
- Giving a group a vague name like "Other stuff". The name must tell what is inside.