01 · One thing happened, done
Ayer fui al mercado.
Yesterday I went to the market.
Fui has a finish line — you went, it's over. That's the preterite's whole job: one completed trip.
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Time Machine
Choose fui or iba on the fly — events, habits, scenes — out loud.
The choice is about meaning, not conjugation tables. The preterite is for completed events with an endpoint: ayer fui al mercado, mi hermana llegó a las ocho. The imperfect is for habits, descriptions and ongoing states: siempre íbamos a la playa en verano, hacía mucho calor ese día. They combine in one signature frame — imperfect for what was happening, preterite for what interrupted it: mientras comía, sonó el teléfono. Time markers do half the work: ayer, anoche, la semana pasada cue preterite; siempre, todos los días, cuando era niño cue imperfect.
Below: the sentences that make each rule stick, the verbs that change meaning between the two tenses (sabía vs supe) — and a way to practice the choice where it actually gets made: mid-sentence, out loud, in a real conversation. No drills.
The warm-up pack
The eleven sentences where fui and iba actually get chosen — not conjugated, chosen.
01 · One thing happened, done
Ayer fui al mercado.
Yesterday I went to the market.
Fui has a finish line — you went, it's over. That's the preterite's whole job: one completed trip.
02 · A moment with a clock time
Mi hermana llegó a las ocho.
My sister arrived at eight.
A specific clock time (a las ocho) almost always drags the verb into preterite — it pins the event to one moment.
03 · What you always did as a kid
De niño jugaba al fútbol todos los días.
As a child I played soccer every day.
Jugaba paints something you did over and over as a kid, not once. No endpoint, so it's imperfect.
04 · Every summer, no exceptions
Siempre íbamos a la playa en verano.
We always went to the beach in summer.
Siempre is the imperfect's favorite word — it flags a habit before you even choose the verb.
05 · Setting the scene
Hacía mucho calor ese día.
It was very hot that day.
Weather and background scenery are imperfect almost by default — they're the wallpaper, not the event.
06 · Painting the mood
Era una noche tranquila.
It was a quiet night.
Era sets a mood, not a fact with a start and end. That's the tell for imperfect over fui or fue.
07 · The interruption pattern
Mientras comía, sonó el teléfono.
While I was eating, the phone rang.
This is the frame that does the real work: comía is the ongoing scene, sonó is what cut into it. Learn this pair and the choice stops being a guess.
08 · Same pattern, different verb
Cuando salí, empezó a llover.
When I went out, it started to rain.
Same shape, new verbs — salí is the interruption, empezó is what followed. Once you've got it once, it repeats everywhere.
09 · Knew it already
Sabía la respuesta desde ayer.
I had known the answer since yesterday.
Sabía means you already had the answer — an ongoing state, not a moment. Imperfect.
10 · Found out just now
Supe la verdad anoche.
I found out the truth last night.
Supe means the moment it clicked — you found out. Same verb as card 09, totally different meaning depending on the tense.
11 · Met her, not knew her
Conocí a tu madre en la fiesta.
I met your mother at the party.
Conocí only ever means met for the first time. Say conocía instead and you're claiming you already knew her.
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Ten-minute spoken lessons. A teacher who answers back — and gently fixes what you got wrong.
First 10 lessons freeandbefluent.com/spanish/time-machineRegional Spanish
Textbooks teach one word. Locals use several — pick your region's and stay consistent.
Watch out
The part no drill site can do
Carla
Your grammar teacher for this pack
You won't conjugate a single list in the Time Machine lessons — you tell your own past, out loud, and Carla coaches the choices as you make them. She asks about your weekend, and you frame it like a native: one imperfect line for the mood (era una noche tranquila), preterite for what actually happened (anoche cenamos en casa). She throws you a marker — siempre, anoche, todos los días — and you build the sentence on the spot, until picking the tense stops being a decision at all.
Blank mid-sentence and nothing bad happens — she waits. That's the practice, without unnecessary judgement.
Finish the 6 lessons and Time Machine is yours — earned, not given.
First 10 lessons free · 10-minute spoken lessons · your AI coaching team remembers you
Quick answers
The preterite reports a completed event with a clear endpoint: terminé el libro el sábado. The imperfect paints what the past was like — habits (mi abuela cocinaba los domingos), descriptions (la casa tenía un jardín grande), and ongoing states (estaba cansado y quería dormir).
Ayer, anoche, la semana pasada, el año pasado → preterite. Siempre, todos los días, de niño, cuando era joven → imperfect. Native speakers treat these pairings as automatic.
Sabía = I knew (ongoing); supe = I found out (the moment of discovery): supe la verdad anoche. Same shift with conocer: conocía a Juan desde la universidad (knew him) vs conocí a tu madre en la fiesta (met her).
Mientras comía… — imperfect for the ongoing action, preterite for whatever cut in: mientras comía, sonó el teléfono. Saying mientras comí is the classic giveaway mistake.
For a finished event, Latin American Spanish strongly prefers the preterite — ayer fui al mercado — where Spain often uses the compound past (he ido). If you're learning for Latin America, the preterite is the workhorse tense.