Cada vs Toda/o(s)

Question

Rather than giving a dozen examples (which frankly seem as though could be interchangeable) I wish this section would begin with usage rules... under what general circumstances does one typically apply cada vs toda? And then under each rule place the examples to illustrate and underscore.

Silvia Piriz · Accepted Answer

Hola Marco G.
That’s a very fair point and I understand what you’re asking for. The short answer is that cada and todo/a(s) are not interchangeable, even if some examples may look similar at first glance.
Here are the key usage rules in a simplified way:
Cada

Focuses on individual units, one by one

It is always singular

Often used for routines, schedules, or repeated actions

Examples:
Cada día estudio español. (Each day, individually)
Cada persona es diferente.
Todo / toda / todos / todas

Refers to the whole group or totality

Agrees in gender and number with the noun

Emphasises completeness rather than repetition

Examples:
Todo el día estudié español. (The entire day as a whole)
Todas las personas son diferentes.
So while both can translate to “every” in English, the conceptual focus is different:

cada = distributive (one by one)

todo(s) = collective (the whole set)

You’re absolutely right that starting with rules and then illustrating them with examples can make the distinction clearer, especially at early levels. I’ll pass this feedback on to the content team — it’s very constructive.
Thanks for taking the time to reflect on the structure of the lesson and for sharing your learning perspective.
Un saludo, Silvia