Order by typical adult weight, lightest first. You place all 30 cards in the right order, one at a time. You start with three lives, and ten right in a row wins a lost one back.
Each card names a living animal and prints its class underneath, so you can tell a bird from a reptile at a glance. You rank them by typical adult weight in kilograms, lightest at the start of the line. One animal goes down first with its weight in view. Choose a gap for every new card. Get it right and the weight appears; get it wrong and the animal still moves to its proper place, but one of your three lives is gone.
The range is enormous, running from creatures you could post in an envelope to giants that can only be weighed in pieces, so most calls come down to picturing the two animals side by side. Birds trick people because feathers hide how little is underneath. Height can mislead you too, and a tall animal isn't always the heavier one. Figures are midpoints for grown adults, so picture an average individual and set aside the record breakers.
Here are 28 of the 30 cards you might be dealt, with 2 more in the deck. Their values stay hidden until you place them.