Neuter article "lo"

Question

The lesson says: Notice how, sometimes despite using the singular "lo + adjective" (lo menos caro), we conjugate the verb in the plural form (son). This is because, being a neutral idea, it can refer to a group of things, i.e "The least expensive things..."

This wording is not clear to me. Do you mean to say that the verb is single or plural depending on the object of the sentence? For example:

Lo más impresionante del viaje fue la cantidad de museos interesantes.

"la cantidad" is single, so "fue" (single) is used - is that correct?

Lo menos caro de esta tienda son los accesorios.

And here, "los accesorios" is plural, hence "son" (plural) - correct?

Silvia Píriz · Answer

Hola Linda L.
Yes, that's exactly the idea.
With lo + adjective, the verb agrees with what that neutral expression is actually referring to.
In your first example:
Lo más impresionante del viaje fue la cantidad de museos interesantes.
Here, lo más impresionante del viaje refers to la cantidad de museos interesantes, which is singular, so fue is the correct form.
In the second example:
Lo menos caro de esta tienda son los accesorios.
Here, lo menos caro refers to los accesorios, which is plural, so son is used.
Thank you for pointing this out. We agree that the wording in the lesson could be clearer, and we'll update it to make it more explicit that the verb agrees with the noun or idea that lo + adjective refers to.
Hasta pronto
Silvia