Spanish Homework Help: Common Grammar Mistakes to Avoid

TL;DR

• The Big Three pain points for English speakers: ser/estar, preterite/imperfect, and the subjunctive mood
• Ser = permanent/inherent characteristics. Estar = temporary states/locations. But there are important exceptions
• Preterite = completed actions. Imperfect = ongoing/habitual past actions. Think "snapshot vs. movie"
• The subjunctive triggers can be memorized with the acronym WEIRDO (Wishes, Emotions, Impersonal expressions, Recommendations, Doubt, Ojalá)

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Spanish homework can be frustrating. You've memorized the vocabulary, you get the general meaning of sentences, but then you write something and your teacher marks it up with corrections that don't seem to make sense.

"Why is it 'es' here but 'está' there? They both mean 'is'!"

Yeah, I hear you. English has one word for "is." Spanish has two. And that's just the beginning of the grammar differences that trip English speakers up.

Let's go through the most common mistakes and actually explain the logic behind the rules. Because once you understand the why, the grammar stops being random and starts being predictable.

Mistake #1: Confusing Ser and Estar

Both mean "to be." But they're used in completely different situations.

Ser: The Essence

Use ser for things that are inherent, permanent, or defining characteristics:

• Identity: Soy estudiante (I'm a student)
• Origin: Ella es de México (She's from Mexico)
• Physical description (inherent): El libro es rojo (The book is red)
• Personality: Mi hermano es inteligente (My brother is intelligent)
• Time/date: Son las tres (It's three o'clock)
• Occupation: Somos profesores (We're teachers)
• Relationships: Ella es mi madre (She's my mother)
• Material: La mesa es de madera (The table is made of wood)

Memory trick — DOCTOR: Description, Occupation, Characteristic, Time, Origin, Relationship

Estar: The State

Use estar for things that are temporary, changeable, or about condition/location:

• Location: Estoy en la biblioteca (I'm in the library)
• Emotions: Estoy feliz (I'm happy [right now])
• Physical condition: Está enferma (She's sick)
• Weather (how it feels): Está nublado (It's cloudy)
• Progressive tense: Estoy estudiando (I'm studying)
• Result of an action: La puerta está cerrada (The door is closed [someone closed it])

Memory trick — PLACE: Position, Location, Action (progressive), Condition, Emotion

The Tricky Cases

Some adjectives change meaning depending on which verb you use:

Adjective	With SER	With ESTAR
aburrido	boring (inherent quality)	bored (current state)
listo	clever (personality)	ready (temporary state)
malo	bad/evil (character)	sick (condition)
rico	rich (wealth)	delicious (tasting it now)
verde	green (color)	unripe (state)
vivo	lively/clever (personality)	alive (state of being alive)

Example:

• "La película es aburrida" = The movie IS boring (the movie itself is boring)
• "Estoy aburrido" = I AM bored (my current emotional state)

The "Dead" Test

Not sure which to use? Ask yourself: would this still be true if the person were dead?

• "Es inteligente" → Was the person intelligent when alive? Yes → ser ✓
• "Está cansada" → Is the person tired when dead? No → estar ✓

It's a morbid trick but it works for most cases.

Mistake #2: Preterite vs. Imperfect

Both are past tenses. Both describe things that happened before now. The difference is in how you view the action.

Preterite: The Snapshot

Use the preterite for actions that:

• Started and ended at a specific time
• Happened a specific number of times
• Are completed events

Think of it as a photograph — a single moment, frozen.

Examples:

• Ayer comí pizza (Yesterday I ate pizza — one specific instance)
• Viajé a España en 2024 (I traveled to Spain in 2024 — completed trip)
• Llamé tres veces (I called three times — specific count)
• La película empezó a las ocho (The movie started at eight — specific moment)

Key trigger words: ayer (yesterday), anoche (last night), una vez (once), de repente (suddenly), el año pasado (last year)

Imperfect: The Movie

Use the imperfect for actions that:

• Were ongoing or habitual in the past
• Set the scene or describe background
• Had no specific start or end point

Think of it as a movie — continuous, flowing, unfinished.

Examples:

• Cuando era niño, jugaba al fútbol (When I was a kid, I used to play soccer — habitual)
• Hacía sol y los pájaros cantaban (It was sunny and the birds were singing — setting the scene)
• Tenía quince años (I was fifteen — ongoing state)
• Siempre comíamos juntos (We always ate together — habitual)

Key trigger words: siempre (always), a menudo (often), todos los días (every day), mientras (while), de niño/a (as a child), generalmente (generally)

Using Both Together

This is where it gets interesting. In a narrative, you often use both:

"Caminaba (imperfect — ongoing action) por la calle cuando vi (preterite — specific event) a mi amigo." = "I was walking down the street when I saw my friend."

The imperfect sets the scene (what was already happening). The preterite interrupts with a specific event.

Formula: Imperfect (background) + Preterite (event) = Classic narrative structure

More examples:

• "Dormía cuando sonó el teléfono" (I was sleeping when the phone rang)
• "Llovía y hacía frío cuando llegamos" (It was raining and cold when we arrived)

Mistake #3: The Subjunctive

The subjunctive is the grammar concept that makes students want to flip a table. English barely uses it (though we do: "I wish I were rich" uses the subjunctive). Spanish uses it constantly.

What Is the Subjunctive?

The subjunctive is a mood (not a tense) that expresses things that are:

• Uncertain (doubt, possibility)
• Desired but not factual (wishes, hopes, commands)
• Emotional reactions (being happy, sad, angry about something)
• Hypothetical (things that may or may not happen)

When to Use It: WEIRDO

W — Wishes and desires: Quiero que tú estudies (I want you to study)

E — Emotions: Me alegra que estés aquí (I'm glad you're here)

I — Impersonal expressions: Es importante que hagas la tarea (It's important that you do the homework)

R — Recommendations/Requests: Recomiendo que vayas al médico (I recommend you go to the doctor)

D — Doubt/Denial: Dudo que sepa la respuesta (I doubt he knows the answer)

O — Ojalá: Ojalá que llueva (I hope it rains) — Ojalá always triggers subjunctive

The Key Rule

The subjunctive appears in the subordinate clause (after "que") when the main clause involves WEIRDO emotions/attitudes AND the subjects are different.

Subjunctive: Quiero que tú estudies (I want [that] you study — two different subjects) NOT subjunctive: Quiero estudiar (I want to study — same subject, use infinitive)

Common Subjunctive Triggers

Trigger	Example
querer que	Quiero que vengas
esperar que	Espero que estés bien
es necesario que	Es necesario que practiques
dudar que	Dudo que sea verdad
no creer que	No creo que pueda
tener miedo de que	Tengo miedo de que llueva
ojalá que	Ojalá que ganes
para que	Estudio para que aprenda
antes de que	Antes de que te vayas

Mistake #4: Gender Agreement

Everything in Spanish has a gender: nouns, adjectives, articles. English speakers forget to make them match.

Rules:

• Most nouns ending in -o are masculine: el libro, el gato
• Most nouns ending in -a are feminine: la mesa, la casa
• Adjectives must match: el gato negro, la casa blanca
• Plurals must match too: los gatos negros, las casas blancas

Common exceptions to memorize:

• el día (day) — masculine despite ending in -a
• el problema — masculine (Greek origin words ending in -ma are usually masculine)
• el mapa — masculine
• la mano (hand) — feminine despite ending in -o
• la foto — feminine (short for fotografía)

Mistake #5: False Cognates

Words that look like English words but mean something different:

Spanish	You think it means	It actually means
embarazada	embarrassed	pregnant
constipado	constipated	has a cold
actualmente	actually	currently
realizar	to realize	to carry out/accomplish
sensible	sensible	sensitive
éxito	exit	success
asistir	to assist	to attend
librería	library	bookstore

Memorize these. They show up on exams constantly, and using them wrong can lead to hilarious (or embarrassing) misunderstandings.

Mistake #6: Direct and Indirect Object Pronouns

English: "I gave the book to her." Spanish: "Se lo di." (Literally: To-her it I-gave)

The pronoun goes BEFORE the conjugated verb (or attached to infinitives/gerunds):

Direct object pronouns (what): me, te, lo/la, nos, os, los/las Indirect object pronouns (to/for whom): me, te, le, nos, os, les

When both appear together, indirect comes first. And le/les changes to se before lo/la/los/las:

• Le doy el libro → Se lo doy (I give it to him/her)
• Les compro flores → Se las compro (I buy them [flowers] for them)

Study Tips for Spanish

1. Practice Out Loud

Language is meant to be spoken. Read your homework answers aloud. Listen to Spanish music, podcasts, or TV shows. Your brain processes language differently when you hear and speak it versus just reading it.

2. Drill the Conjugations

There's no shortcut. You need to know verb conjugations well enough that they're automatic. Use flashcards with spaced repetition — they're incredibly effective for language patterns.

3. Read in Spanish

Start simple: children's books, news articles written for learners, social media posts. Reading builds vocabulary and exposes you to grammar patterns in context.

4. Make Mistakes On Purpose

The best way to learn grammar is to use it, get corrected, and try again. Write sentences using the grammar points you struggle with and ask your teacher or an AI tool to correct them.

5. Use AI for Practice

Gradily can help you practice grammar concepts by generating exercises, explaining why a specific form is correct, and giving you instant feedback on your answers. Ask things like "Why is it estar and not ser in this sentence?" and you'll get a clear explanation.

The Mindset for Spanish Grammar

Here's what helped me most: stop trying to translate from English. English and Spanish organize ideas differently. Instead of thinking "how do I say this English sentence in Spanish," try to think directly in Spanish patterns.

This feels impossible at first. But the more you practice, the more natural it becomes. One day you'll conjugate a subjunctive verb without even thinking about it — and that's when you know the grammar has really clicked.

Spanish grammar has rules, and the rules make sense once you understand the underlying logic. Ser vs. estar is about essence vs. state. Preterite vs. imperfect is about completed vs. ongoing. The subjunctive is about uncertainty vs. certainty.

Learn the logic, practice the patterns, and give yourself permission to make mistakes along the way. That's how language learning works — for everyone, not just the people who seem to "get it" naturally.

¡Buena suerte!