Haben, Tun and Machen

Hallo! I am learning lesson 4.6 Haben, Tun and Machen. The singular form for du is machst. But I remember in lesson 3.3 In die Stadt fahren, Paul is using: Was willst du heute machen?
I thought if according to the grammar, it should be: Was willst du heute machst?

Vielen dank for the answers!

Hi Linie, this sentence uses the verb wollen (du willst). This is a modal verb which is used with the infinitive of another verb placed at the end of the sentence. 
Was willst du heute machen?
What do you want to do today?
So machen has to be infinitive. 

There is a video about wanting things on Lingoni (ex German with Jenny)
https://www.youtube.com/watch?v=hB9AnBkBv2o&t=205s
The site also has several other videos  about modal verbs.

Hi Linie and sfpugh, 

Thank you for your question. Sfpugh is right, wollen is a modal verb. Other German modal verbs are können, dürfen, sollen, müssen and mögen.

Whenever there is a sentence with a modal verb and an infinitive (machen in this case), the infinitive is always placed at the end of the sentence or clause. 

Let me give you some more examples:
"Ich will heute Nudeln essen." - "I want to eat pasta today."
"Er kann das Deutsch sprechen." -"He can speak German."
"Sie muss das machen." - "She has to do that." 

You can learn more about German word order and modal verbs in lesson 7.6 Word Order Rules, lesson 6.8  Helping Verbs: KÖNNEN and SOLLEN and lesson 6.9 Helping Verbs: MÜSSEN and DÜRFEN.

Viele Grüße
Julia
 

Thanks Julia and Sfpugh for the answers.

Btw, Sfpugh, you're really good in German. How long have you been learning German?

-Linie

Thanks Linie, I have been learning German for about 3 years. I completed Rocket German level 3 over a year ago, but I come back from time to time for revision.

I also did Deutsche Welle's course Nicos Weg. https://www.dw.com/de/deutsch-lernen/deutsch-mobil/s-40884569
Levels A1 and A2 cover much the same material as Rocket, but in a very different way so it is good from that point of view. It has has a B1 course. Currently am am having conversation lessons with a tutor on iTalki.

Hi Sfpugh,

Wow!!  I'm still a baby learner now, but hope I will be able to understand more of the grammar usage.  Thanks for all those recommendation course :)

-Linie