Systematic Listing
Enumerate possibilities of combinations of two variables systematically (e.g. all ways to choose from a set of options)
What a learner can do afterwards
- List all possible meal combinations from 3 starters and 4 mains
- Organise combinations into a systematic table to ensure none are missed
- Explain why the total number of combinations equals the product of the options in each category
The lesson
A combination is one choice from each group, put together. If you have 3 T-shirt colours and 2 trouser colours, each outfit combines one shirt colour with one trouser colour. To list every combination without missing any, go through the colours in order instead of guessing.
A cafe offers 3 starters and 4 mains. Pick the first starter and pair it with each of the 4 mains. Then move to the second starter and pair it with each main again. Keep going until every starter has been paired with every main. This gives 3 x 4 = 12 meal combinations.
Work through one group in order, pairing each item with every item in the other group before moving on. This systematic method stops you skipping a pair or writing the same one twice.
List combinations one group at a time, and the total always equals the two group sizes multiplied together.
Watch it
Where it sits
Learn first
This opens up
Nothing builds on it yet.
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.