Mind

A bizarre Christmas dinner invitation, some mysterious carol singers and even a spot of charades. Can you solve all 12 of our unique festive riddles?

By Leonie Mercedes

10 December 2025

Sam Peet

Here are twelve tricksy Christmas riddles with a scientific twist. Can you solve them all? When you’re ready, scroll down for the answers.

(1) What an honour! You have been invited to dine with a host of mythological figures, nine Nobel prizewinners and a few noble types, who tend to keep themselves to themselves. To where have you been invited?

(2) Our local, friendly scientist has sent us a homemade Christmas card, how sweet. It looks like they have created the message on the front with some odds and ends they found around the lab… let’s see:

• The symbol for the SI unit of force, named for a polymath who did weighty and illuminating work in the 17th century, cut out of a physics textbook
• The name of the most common blood type, snipped out of a pamphlet
• The symbol for a number equal to about 2.718, clipped from a poster of mathematical constants
• An abbreviation denoting the “father of taxonomy”, torn from a specimen jar label

What does the message say?

(3) I have been used to create images, heal injuries and deliver calories. At this time of year, you might find me on the Christmas tree. What am I?

(4) Ding dong! What’s that I hear at the door? Oh, the carollers have returned! And who have we here? Why, it is the discoverer of pulsars, the CERN physicist whose eponymous test proves the quantum nature of reality and the patent holder of the first practical telephone. What are they singing?

(5) The hosts have decided to serve a powerful menu this year, with each course being 1000 times bigger than the last (and that’s no exaggeration). What festive biscuit might come next in this procession of courses? Nachos, minestrone, milk chocolate – break to catch our breath – kimchi, melon sorbet… ?

(6) Pull up a few more seats! We have some extra dinner guests: the first computer programmer, the palaeontologist who, according to legend, “sold seashells on the seashore”, the mathematician and broadcaster with the social media handle @fryrsquared and the most recent common ancestor of all human beings. On reflection, who won’t be returning next year?

(7) How does adding energy, and a unit of energy, to a monk who worked with peas and a paintbrush give you an organised chemist?

(8) Listen carefully because we won’t be repeating this one. What year could logically follow this sequence: a dwarf planet first observed in 2005, a soft, continuous sound and the term for a cultural item that is repeated and adapted, notably online, first used by Richard Dawkins in 1976?

(9) Dinner eaten and plates cleared, it is time for the final, spectacular flourish. The lights are lowered so we can see it better: a vapour of ethanol reacting with oxygen to produce carbon dioxide and water, leaving the structure beneath unscathed. What just happened?

(10) No one can beat Grandma at charades. She’s truly a maestro of the form. She just acted out the following for us:

• A branch of physics relying on Newtonian mechanics
• An item often licked by geologists
• The sixth derivative of position
• Two prehistoric species of marine mollusc, whose names derive from their spiky appearance.

What theme unites them?

(11) I have been described as an ecosystem, hosting billions of inhabitants, but you would never hear from them. Versions of me have existed since the Stone Age, but put me on the dining table and I won’t last long at all. What am I?

(12) Let’s see if you can crack this one. Santa has hidden some treats in this clutch of clues:

• The medical term for sneezing
• A semiaquatic rodent also known as a coypu
• The SI unit for time multiplied by 60
• The last of the seven life processes in the acronym MRS GREN.

What are the treats, and where might you find them on Christmas Day?

Sam Peet

(**1) **You have been invited to sit at the periodic table. Among those mythological figures, and the elements named after them, are the 12 titans (titanium), Prometheus (promethium) and Thor (thorium). The Nobel prizewinners and their element namesakes include Ernest Rutherford (rutherfordium), Marie Skłodowska-Curie and Pierre Curie (curium) and Albert Einstein (einsteinium). The “noble types” are the noble gases, which sit on the far-right-hand side of the periodic table.

(2) The word on the card is Noel (or, more accurately, NOeL). N is the symbol for newtons, O is the most common blood type, e is a mathematical constant and L. on specimen labels indicates that Carl Linnaeus named a species.

(3) Element 47 has been used through the ages. It creates images in a few ways: silver salts are used in photography, and silver itself is used in mirrors. Silver ions or compounds are included in wound dressings due to their antimicrobial properties. Silverware delivers calories in the form of knives, forks and spoons, and if you have shiny, glass baubles on your Christmas tree, that lustre may be due to a thin layer of silver inside.

(4) Why, it is the Carol of the Bells. In order, these describe astronomer Jocelyn Bell Burnell, physicist John Stewart Bell and inventor Alexander Graham Bell.

(5) Gingerbread would be an acceptable answer. Our dishes share their first two letters with the most commonly used metric prefixes (words that make a number bigger or smaller by powers of 10) stepping up regularly from the tiny (nano) to the massive (giga). In order, they are: nano (10-9), micro (10-6), milli (10-3), a break for 100 (which equals 1), kilo (103), mega (106) and giga (109).

(6) These describe Ada Lovelace, Mary Anning, Hannah Fry and mitochondrial Eve. Mary Anning is the only one without a palindromic first name, i.e. one that reads the same forwards and backwards (or on the return), so she is the one who won’t be coming back next year.

(7) Add the symbol for energy, E, and a symbol for a unit of energy, eV (the electronvolt), to Mendel to get Mendeleev. Gregor Mendel demonstrated how traits are inherited in a series of breeding experiments on pea plants in the 1850s and 1860s, while Dmitri Mendeleev created the first periodic table by putting the chemical elements in order of atomic weight.

(8) The three clues describe Makemake, murmur and meme. Each of these words is made of a repeated unit that gets one letter shorter each time, so the year MM (2000 in Roman numerals) could logically follow.

(9) The Christmas pudding has been set alight! The brandy must be warmed before being poured over it, so that the ethanol vapour from the alcohol burns, and not the pud.

(10) The theme of Grandma’s charades was music. The clues refer to classical, rock, pop and, finally, punk and emo.

(11) It is cheese. Humans have been making cheese in one form or another for more than 7000 years. It gets its flavour and texture from the many varieties of bacteria, moulds and yeasts that live within.

(12) The answer is nuts. Each clue describes a word that contains the word “nut”: sternutation, nutria, minute, nutrition. You might find these in your stocking, or perhaps on the table after dinner.

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