Learn Hardcore Spanish (Latin America): El profesor va a medir cada lado del triángulo. - The teacher is going to measure each side of the triangle.

So va a medir literally is is going to measure, and it’s used to talk about the near or planned future. In everyday Latin American Spanish, ir a + infinitive is often more common than the simple future for spoken language when talking about plans or intentions.

Could I say El profesor medirá cada lado del triángulo instead? Does it mean the same thing?

Yes, you can say El profesor medirá cada lado del triángulo, and it is correct.

va a medir = is going to measure (planned/near future, very common in speech)
medirá = will measure (simple future, a bit more formal or neutral)

In many contexts, they mean essentially the same. In Latin American everyday speech, va a medir sounds a bit more natural and conversational, while medirá can sound slightly more formal or written, but both are fine.

If I want to say “The teacher is measuring each side of the triangle” (right now), would I still use va a medir?

No. To express an action happening right now, Spanish usually uses the present progressive:

El profesor está midiendo cada lado del triángulo.
= The teacher is measuring each side of the triangle (right now).

Compare:

va a medir → is going to measure (future plan)
está midiendo → is measuring (currently in progress)

Why do we use el in El profesor va a medir…? Can I drop the article like in English sometimes?

In this sentence, el is required because we are talking about a specific teacher:

El profesor va a medir… = The teacher is going to measure… (a specific one)

In Spanish:

When you talk about a specific person with their profession, you normally use the definite article:
El profesor llegó temprano. – The teacher arrived early.
You omit the article mainly after ser when describing someone’s profession in general:
Él es profesor. – He is a teacher.

So here, you should not drop el. Saying just Profesor va a medir… is not natural Standard Spanish.

What is the difference between profesor and maestro in Latin America?

Usage varies a bit by country, but in much of Latin America:

profesor / profesora
- Often used for middle school, high school, and university teachers.
- Also used more generally and politely for teacher or instructor.
maestro / maestra
- Very commonly used for elementary/primary school teachers.
- Can also mean master of a craft or skill (e.g. maestro de obra = foreman in construction).

In many contexts, people will understand both, but profesor sounds a bit more formal/academic, and maestro more like grade-school teacher or a respectful, sometimes warmer term.

Why is it cada lado and not cada lados or cada de los lados?

Cada has some special rules:

Cada is always followed by a singular noun:
- cada lado – each side
- cada estudiante – each student
- You do not say cada lados or cadas (there is no plural form of cada).
You do not add an article between cada and the noun:
- cada lado (correct)
- cada los lados (incorrect)
- cada de los lados (incorrect in this meaning)

So the correct form is cada + singular noun: cada lado, cada niño, cada día, etc.

What is the difference between cada lado and todos los lados?

Both refer to all the sides, but the emphasis is slightly different:

cada lado del triángulo
– Literally each side of the triangle.
– Emphasizes the sides one by one, individually.
– Fits well with an action that is repeated for each element.
todos los lados del triángulo
– All the sides of the triangle.
– Emphasizes the group as a whole (the complete set).

In your sentence, El profesor va a medir cada lado del triángulo, the idea is that he will measure them one by one, which is why cada is very natural here.

Why is it del triángulo and not de el triángulo?

In Spanish, de + el contracts to del:

de el triángulo → del triángulo

This contraction is mandatory; you cannot write or say de el separately (except in very rare special cases like emphasis in poetry or when el is part of a name).

Other common examples:

de el libro → del libro
de el profesor → del profesor

Why is it el triángulo and not la triángulo? Is there a rule for its gender?

Triángulo is masculine, so it takes el: el triángulo.

General patterns (with many exceptions, but helpful):

Nouns ending in -o are usually masculine:
el triángulo, el círculo, el cuadrado, el libro
Nouns ending in -a are usually feminine:
la casa, la mesa, la silla

Many geometric shapes in Spanish are masculine:

el círculo, el cuadrado, el rectángulo, el triángulo, el rombo

There is no deep logic behind why a particular noun is masculine or feminine; it’s mostly conventional. The safest approach is to learn el triángulo as a fixed chunk: article + noun together.

How would the sentence change if the teacher is a woman?

You would change el profesor to la profesora. The rest of the sentence stays the same:

La profesora va a medir cada lado del triángulo.

Profesor (male) → profesora (female)
The verb va does not change because the verb form is the same for he and she in Spanish (él va, ella va).

Why does triángulo have an accent mark on the a, and how should I pronounce it?

The accent mark in triángulo shows where the stress falls.

Syllables: tri-án-gu-lo

Without the accent, by default the stress would be on the penultimate syllable (-gu-): trian-GU-lo.
With the accent on á, the stress moves to án: tri-ÁN-gu-lo.

Pronunciation guide:

tri – like tree (but a bit shorter)
án – like ahn, with the stress here
gu – like goo (the g is hard, as in go)
lo – like lo in lot but without the final t

Approximate English-style pronunciation: tree-AHN-goo-lo.
The accent tells you to stress the ÁN part.

How do you pronounce medir, and is it an irregular verb?

Pronunciation:

medir is pronounced approximately meh-DEER.
- me- like meh
- -dir like deer, but with a softer d (between vowels, Spanish d is often softer, similar to the th in this in many accents).

Irregularity:

Yes, medir is a stem-changing verb (e → i) in the present tense:

yo mido – I measure
tú mides – you measure
él/ella mide – he/she measures
nosotros medimos – we measure (no change)
ellos miden – they measure

In va a medir, the verb is in the infinitive (medir), so you don’t see the stem change there. The change appears when you conjugate medir directly, like mide, miden, mido, etc.

Can I change the word order, for example El profesor cada lado del triángulo va a medir?

The normal, most natural word order here is:

El profesor va a medir cada lado del triángulo.
(Subject – Verb – Object – Complement)

Spanish word order is somewhat flexible, but not every permutation sounds natural.
Your example El profesor cada lado del triángulo va a medir sounds strange in standard speech and would at best be very marked/poetic.

Some variations that are possible (with different emphasis) are:

Cada lado del triángulo lo va a medir el profesor.
(Emphasis on each side of the triangle; also uses the pronoun lo.)
El profesor va a medir los lados del triángulo, cada uno.
(Stylistic variation, split into two ideas.)

For a learner and for neutral, correct Spanish, stick with:

El profesor va a medir cada lado del triángulo.