1. Saying what someone is/was going to do
Ir + a + infinitivo
Saying what someone is/was going to do
I’m going to study a lot.
Voy a estudiar mucho.

2. Use ir + a + infinitivo to say
what someone was going to do in the past.
Elena and I were going to go shopping.
Elena y yo íbamos a ir de compras.
I wasn’t going to buy anything.
No iba a comprar nada.
I was going to call you yesterday.
Iba a llamarte ayer.

3. You can add to these sentences by saying what happened instead, using the preterite (what interrupted the plans).
Elena and I were going to go shopping, but she had to study.
Elena y yo íbamos a ir de compras, pero tuvo que estudiar.
I wasn’t going to buy anything, but they gave me a discount.
No iba a comprar nada, pero me dieron un descuento.
I was going to call you yesterday, but I got home too late.
Iba a llamarte ayer, pero llegué a casa demasiado tarde.

4. You can also elaborate by giving more background information, using the imperfect.
They were going to visit the market, but they were really tired.
Iban a visitar el mercado, pero estaban muy cansados.