In mathematics, we have sets, such as $\begin{Bmatrix}1, 2, 3 \end{Bmatrix}$ or the real-numbers, usually denoted as $\mathbb{R}$.
When teaching students about sets for the first time, it can sometimes (not always, but sometimes) be nice to make an semi-intuitive analogy to real-life.
What collection of 3 to 10 words in the English language can we use to represent a mathematical set?
Ideally...
There exists two sets $A$ and $B$ in our example such that $A$ and $B$ overlap ($A \cap B \neq \emptyset$)
There exists a universal set labeled $(\alpha\Omega)$ in our example such that $A \subseteq (\alpha\Omega)$ and $B \subseteq (\alpha\Omega)$ and $A \cup B \neq (\alpha\Omega)$
We could ask students for such an example, except that we are teaching student who do not already know what a set is.
These students have never heard the words "union" or "intersection" used in math-class before.
Our goal is to choose a handful of words from every day English in order to provide an analogy for what a set is.
Someday, I would like to present students with many examples of this, but I am having difficulty thinking of more than three examples.