A clear study guide to master the two Spanish past tenses, with practice and answers.
If you’re working through a preterite vs imperfect worksheet (like the ones on Conjuguemos) and want to make sure you understand the rules, this guide has you covered. Below you’ll find a clear breakdown of when to use each past tense, the trigger words that signal them, and an original practice set with a full answer key so you can check your own work and actually learn the concept.
Note: This is a study guide to help you understand preterite vs imperfect, not the official answer key to any specific Conjuguemos assignment. Use it to learn the rules so you can complete your own worksheet confidently.
The Core Difference
Both the preterite and the imperfect are past tenses, but they describe the past differently.
- Preterite = completed actions. A specific event that started and finished (“Comí” / I ate).
- Imperfect = ongoing, habitual, or background actions. What “used to” or “was” happening (“Comía” / I was eating / used to eat).
When to Use Each Tense
| Use Preterite for… | Use Imperfect for… |
|---|---|
| A completed, one-time action | Ongoing or repeated past actions |
| Actions with a clear beginning/end | Descriptions and background |
| A sequence of events | Time, age, weather, feelings in the past |
| Something that interrupted an action | The action that was interrupted |
Rule of Thumb: If you can say “used to” or “was/were ___ing” in English, use the imperfect. If it’s a finished, specific event, use the preterite.
Trigger Words (Quick Clues)
| Preterite Triggers | Imperfect Triggers |
|---|---|
| ayer (yesterday) | siempre (always) |
| anoche (last night) | todos los días (every day) |
| de repente (suddenly) | mientras (while) |
| una vez (once) | generalmente (generally) |
| el año pasado (last year) | de niño/a (as a child) |
How They Work Together
Often both appear in one sentence: the imperfect sets the scene, and the preterite marks the event that happened.
Yo leía cuando sonó el teléfono. (I was reading [imperfect] when the phone rang [preterite].)
Practice Worksheet
Choose the correct form of the verb in parentheses. Answers are in the key below.
- Ayer yo ______ (comer) en un restaurante nuevo.
- Cuando era niño, ______ (jugar) al fútbol todos los días.
- Nosotros ______ (ver) una película anoche.
- Mientras ella ______ (estudiar), su hermano llegó.
- El año pasado ellos ______ (viajar) a España.
- Siempre ______ (hacer) frío en el invierno.
- De repente, el perro ______ (saltar) la cerca.
- Yo ______ (tener) diez años cuando aprendí a nadar.
- Tú ______ (escribir) la carta ayer por la tarde.
- Generalmente nosotros ______ (ir) a la playa en verano.
Answer Key
Check your answers below. The reason for each choice is in parentheses.
| # | Answer | Tense | Why |
|---|---|---|---|
| 1 | comí | preterite | completed action, “ayer” |
| 2 | jugaba | imperfect | habitual, “todos los días” |
| 3 | vimos | preterite | completed, “anoche” |
| 4 | estudiaba | imperfect | ongoing action interrupted |
| 5 | viajaron | preterite | completed, “el año pasado” |
| 6 | hacía | imperfect | weather description, “siempre” |
| 7 | saltó | preterite | sudden event, “de repente” |
| 8 | tenía | imperfect | age in the past |
| 9 | escribiste | preterite | completed, “ayer” |
| 10 | íbamos | imperfect | habitual, “generalmente” |
Common Mistakes to Avoid
- Using preterite for descriptions or feelings (use imperfect: “Estaba feliz“).
- Using imperfect for a clearly finished event (use preterite: “Llegué a las ocho“).
- Forgetting that “mientras” usually signals the imperfect.
Frequently Asked Questions
What is the main difference between preterite and imperfect?
The preterite describes completed, specific past actions. The imperfect describes ongoing, habitual, or background actions, often translated as “used to” or “was ___ing.”
How do I know which tense to use?
Look for trigger words and meaning. Finished events (ayer, de repente) take the preterite; repeated or ongoing states (siempre, de niño) take the imperfect.
Can both tenses appear in one sentence?
Yes. The imperfect sets the background and the preterite marks the action that happened, as in “Leía cuando sonó el teléfono.”
Is this the official Conjuguemos answer key?
No. This is an independent study guide with original practice and answers to help you learn the rules, so you can complete your own worksheet correctly.
Preterite = done and specific. Imperfect = ongoing or habitual. Learn the triggers and the rest follows.
Benen
My name is Benen, and I am an English teacher from the US and UK. I am passionate about helping people improve their English language skills, including grammar, vocabulary, and sentence structure, while building their confidence in a supportive and patient learning environment.
