Why a shelf is harder than it looks
Mixed days let you use a familiar object as a bridge. A bus explains a whale. A hoop explains a doorway. A category day takes the bridge away and asks you to compare two members of the same family. Two landmarks. Two animals. Two countries. The eye that was borrowing a household object now has to use a ratio inside the family, which is where postcards and textbooks do the most damage. They print the famous one large.
The five pairs are still fixed by your local date, but the draw uses only that shelf. A friend on mixed and a friend on sports are not playing the same puzzle. Say which shelf you used if you compare scores. The weights are unchanged: one, one, two, three, three, and a perfect five is still 1,000.
Animals and vehicles
Animals mix height and length. A giraffe on this board is an adult male to the tips of the horns, about 5.5 metres. An African elephant is head to tail, about 6.5 metres, trunk not stretched forward. An emperor penguin is 1.2 metres standing. A blue whale is 27 metres for a large adult. People shorten whales and lengthen pets. The shelf is there to make that habit visible, because every reference is another body, not a bus you know from the street.
Vehicles are almost all lengths, bumper to bumper or nose to tail. A sports coupe is about 4.52 metres. A bicycle is about 1.75 metres. A school bus is 12. A 747-400 is about 70.7. An ultra-large container ship is about 400. The errors here are powers of ten disguised as confidence. A ship that 'feels like a few buses' is already wrong by an order of magnitude. Say the multiple before you lock in.
Landmarks, everyday things, and sport
Landmarks fail when the picture includes a pedestal one day and a statue the next, and your memory keeps only the statue. This board says which version. Liberty is ground to torch with the pedestal, about 93 metres. The Eiffel Tower includes the antennas, about 330. Elizabeth Tower is the building people call Big Ben. The bell is not the height. Read the fact after you miss. It is usually the whole explanation.
Everyday objects are the opposite problem. You have held them, so you feel accurate, and you are accurate only inside arm's reach. A room, a door, a pitch change the body you compare against. Sport is full of official numbers people have never pictured: a hoop rim at 3.05 metres, a size-5 soccer ball at 0.22 metres across, a size-7 basketball at about 0.24 metres. The rules are exact. The eye is not, until it has put the ball next to the rim on purpose.
Space, plants, and geography
Space is where cropped diagrams live. A rocket, a planet, a telescope: the textbook frame is whatever fitted the page. The board refuses that frame and uses one scale. Expect your first locks to be humble. A ratio of two, which feels like a bold miss in a kitchen, is a mild miss in space and still only scores 45. Five times off scores nothing. The shelf is teaching the log, not the trivia.
Plants are heights that people remember as 'tall' without a number. A coast redwood on this board is Hyperion, the tallest known living tree, rounded. Geography splits in two. Some entries are lengths, Chile north to south at about 4,270 kilometres, Italy's mainland boot at about 1,180. Some are areas, Texas at about 696 thousand square kilometres of land, metropolitan France at about 552 thousand. Never compare a length shelf-mate with an area one. The board will not pair them. The compare page will warn you if you try.
How to use a shelf without memorising it
Play the shelf after a miss, not before a fresh daily five. One animals day will not install a whale in your hand. Three unlimited animals pairs, each with a spoken ratio, will. Then return to mixed. The mixed board is the test. The shelf is the drill. If you only ever play one shelf, you will get good at that family's postcards and stay lost when a bus appears next to a tower.
The cut-out count under each name is the size of the shelf, not a promise that every object appears today. Five rounds need five targets. A small shelf repeats references more often. That is useful. Repetition of the reference is how a 12-metre bus becomes a unit you can feel. The answers for that shelf follow the same date rule as mixed: today stays closed until you finish or you choose to look.