We in the UK also have our young inventors. Samuel Houghton was three when he thought of a double-headed broom, as explained by him in a video compiled for the British Library exhibition Inventing the 21st Century which I curated, back in 2010. I'll admit that I chose him for the cuteness factor, and to show that the young often have very imaginative ideas.
Samuel was lucky enough to be the son of a patent attorney. Dad apparently thought that it would be a useful educational exercise to apply for a British patent (but with no thought of enforcing it). Notice in my list below how the titles, besides the patent claims, are often "broad yet precise" in how they word the concept.
Samuel secured a patent both for this and for a later idea.
Improved broom (but called "Sweeping device with two heads" in a preliminary publication), applied for in 2006, is shown below.
I liked the comment in the granted patent that he "observed that my daddy was wasting time swapping between brushes" when sweeping small or larger fragments. His double-headed broom sweeps both kinds, the front head the big pieces, the back head the smaller ones.
In 2008 there was his Balloon bursting apparatus.
His younger brother Benjamin was responsible in 2008 for Plug for a wash-basin, as illustrated below.
There is one patent in the names of both boys, applied for in 2008. This was Improved handle (at a preliminary stage, titled "Shock-absorbing handle for manual tool"), as illustrated below:
Samuel Houghton has his own Wikipedia article which says "he is thought to be the youngest person to have been granted a patent for their invention", at age 5, though I wonder if Benjamin was younger still. One problem is that the age of invention, applying for and securing a patent are likely to be different and it is often unclear what age applies to what stage when claims are made.
The Guardian has an interview with Samuel Houghton from 2008.