What's about Going to?

Going to is not a tense. It is a special structure that we use to talk about the future.

The structure of going to is:

subject

+

be

+

going

+

to-infinitive

The verb be is conjugated.

subject	be	not	going	to-infinitive
I	am		going	to buy	a new car.
I	'm		going	to go	swimming.

How do we use going to?

going to for intention

We use going to when we have the intention to do something. We have already made a decision before speaking. 

• Jo has won the lottery. He says he's going to buy a Porsche.
• We're not going to paint our bedroom tomorrow.

going to for prediction

We use going to to make a prediction about the future. Our prediction is based on present evidence. We are saying what we think will happen. 

• The sky is very black. It's going to snow.
• It's 8.30! You're going to miss your train!