What are stars? What happens inside a computer? And how are films made?
Those are some of the questions that will be asked in a brand new S4C series for young children, which begins next week.
"Byd Tad-cu" (''Grandpa's World'') will feature two schoolchildren from Barry, who'll be posing the questions to their grandad, played by Danny Grehan.
Accompanied by Heti, a talking rabbit puppet, Tad-cu's answers turn out to be imaginative, impossible and intriguing.
12 year-old Seren Bowen and nine year-old Loti Mai Delve both attend Ysgol Bro Morgannwg - they'll appear as part of a rotating cast of six children from across Wales, who auditioned online for their roles.
Loti said: ''I really enjoyed arriving at the set every morning and getting my make-up and hair done. I loved acting with Heti (the rabbit puppet) and enjoyed filming the Parrot episode where I danced the cha cha cha!''
Seren added: ''It was an amazing experience, which I enjoyed so much.''
''Byd Tad-cu'' is based on the books by Chris Heath and co-produced with Channel 5, who launched an English language version last year.
''The World According to Grandpa'', which airs during Milkshake, stars Don Warrington - best known for his role as Philip in the classic ITV sitcom Rising Damp.
The Welsh-language series was filmed under the tight lockdown restrictions at the start of the year, with funding from the British Film Industry's Young Audiences Content fund - a pilot scheme aimed at supporting creative and inspirational projects.
Sioned Wyn Roberts, S4C's commissioning editor for children's programming, said: ''Grandpa's World is a production full of fun, energy and imagination, which is sure to enchant.
''It's a real pleasure to see talented young actors, most of whom are new faces to the screen.''
The first episode of ''Byd Tad-cu'' can be seen on S4C's Cyw strand on Friday 3rd September at 7.45am.
''Byd Tad-cu'' is a Boom Plant production in partnership with Grandpa Productions and Saffron Cherry.