Blood relations and direction sense: the diagram does the work

Blood relations and direction sense are the two reasoning topics where the difference between a candidate who scores and one who does not is simply whether they picked up a pen. Both are built to punish mental tracking and reward a quick diagram, and both are two or three near-free marks once the diagram is a habit.

Blood relations: build a tiny family tree

Stop translating “my mother’s brother’s son” in your head and draw it. A consistent notation is what makes the tree readable:

• + for male, − for female written beside each person.
• A double line (=) for a married couple, placed side by side.
• A vertical line down for a parent-to-child link, with siblings on the same horizontal level.

Then work outward from the person the sentence starts with, adding one link at a time. The answer is read off the finished tree, not computed. Generations sitting on their own rows is what stops a “grandfather” being mistaken for a “father”.

The three question types

• Direct chains. “The son of my father’s only daughter.” Build left to right and read the end. The word only is load-bearing — it removes ambiguity the setter could otherwise exploit.
• Pointing and introduction. “Pointing to a photo, a woman said…”. Read everything from the speaker’s viewpoint, place the speaker first, and resolve the chain back to the person pointed at.
• Coded relations. Symbols stand for relations: A + B means A is the father of B, and so on. Substitute the symbols into your tree exactly as if they were words; the coding is only a disguise over the same diagram.

Direction sense: axes first, then trace

Draw the compass — north up, east right — put a dot at the start, and trace each leg as a physical line. Two rules remove the errors:

• Turns are relative to your current facing. A left turn is anticlockwise from where you are now, not from north. Mark the new facing after every turn before reading the next instruction.
• Shortest distance is the straight line from start to finish, found by Pythagoras. The legs almost always form a 3–4–5 (or 6–8–10) triangle, so the hypotenuse is instant once you spot it.

For sun-and-shadow questions, remember the sun rises in the east, so in the morning shadows fall to the west, and in the evening to the east; at noon there is effectively no horizontal shadow. That single fact answers the whole shadow family.

A worked reading

“A man walks 4 km north, turns right and walks 3 km. How far is he from the start?” Trace it: 4 km up, then right means now facing east, 3 km across. Start to finish is the hypotenuse of a 3–4 right triangle, so 5 km. Drawn, it is one line; imagined, it is where candidates put the 3 in the wrong direction.

Where the marks leak

Not drawing. The single biggest cause of wrong answers in both topics. The diagram is the method, not an optional aid.

Assuming gender. “The child of my son” is not necessarily a grandson. Leave gender unmarked unless the sentence fixes it.

Turning relative to north. Left and right are relative to your current facing; re-mark the facing after each turn.

Reading a photo question from the wrong side. It is always the speaker’s family, resolved from the far end of the chain back.

Practice that transfers

Both topics improve fastest by drilling the setup, not the deduction. Work through the blood relations and direction sense practice set, drawing every one even when it looks easy, and pair it with the grid discipline in puzzles and seating arrangement, since both come down to representing the problem before solving it.