Learn Hardcore Czech: Myslím, že je lepší být s rodinou než s telefonem. - I think that it is better to be with family than with the phone.

You can say Já myslím, but it is more emphatic, like I think (as opposed to someone else). In neutral speech, Myslím, že… is the most natural.

What is the difference between myslím and myslím si? Could I say Myslím si, že je lepší…?

Both myslím and myslím si are correct here, and both mean I think. The difference is subtle:

myslím – neutral, very common.
myslím si – can sound a bit more personal/subjective, like I believe / I’m of the opinion.

In everyday speech, you will hear both:

Myslím, že je to dobrý nápad.
Myslím si, že je to dobrý nápad.

In your sentence, Myslím, že je lepší… and Myslím si, že je lepší… are both fine.

Why is there a comma before že?

Czech almost always puts a comma before že when it introduces a subordinate clause (a dependent clause).

Myslím, že je lepší…
- Myslím = main clause
- že je lepší být s rodinou než s telefonem = subordinate clause (what you think)

So the comma is required by Czech punctuation rules.

What does že do here? In English I can say I think it’s better… without that. Can I omit že in Czech?

že corresponds to English that (in I think that…).

Myslím, že je lepší… = I think that it is better…

In English, that can often be dropped: I think it’s better…
In Czech, že CANNOT be dropped in this kind of sentence.

You cannot say:

✗ Myslím je lepší být s rodinou…

You must use:

✓ Myslím, že je lepší být s rodinou…

Why is it je lepší být and not just lepší být? What is the role of je?

The structure is:

je lepší být… = it is better to be…

je is the verb být (to be), 3rd person singular present (is).
Czech usually needs this je in such impersonal evaluations:

Je dobré se učit. – It is good to study.
Je těžké to vysvětlit. – It is hard to explain it.
Je lepší být s rodinou. – It is better to be with (the) family.

Without je, the sentence is ungrammatical:

✗ Myslím, že lepší být s rodinou… – wrong
✓ Myslím, že je lepší být s rodinou… – correct

Why is it s rodinou and s telefonem, not s rodina and s telefon?

The preposition s (with) requires the instrumental case.

rodina (family), nominative → s rodinou (with family)
telefon (phone), nominative → s telefonem (with the phone)

So the pattern is:

s + instrumental
- s kamarádem – with a (male) friend
- s mámou – with (my) mum
- s rodinou – with (my/the) family
- s telefonem – with the phone

Using s rodina or s telefon would be wrong, because those are nominative forms, not instrumental.

Why is rodinou spelled with -ou but telefonem with -em?

They belong to different noun declension types.

rodina – feminine noun (ending in -a)
- Instrumental singular: usually -ou
- rodina → s rodinou
telefon – masculine inanimate noun (ending in a consonant)
- Instrumental singular: usually -em
- telefon → s telefonem

So both are just regular instrumental endings for their noun types.

Why is the preposition s and not u or something else? What’s the nuance of s telefonem?

s
- instrumental = with someone/something (in someone’s company, physically together)
  - být s rodinou – to be with family
  - být s telefonem – (literally) to be with the phone, spending time with it

Other prepositions mean something else:

u telefonu – at/by the phone (e.g. answering a call)
u rodiny – at the family’s place (at their house), not with them in general

Your sentence contrasts the company you keep:

být s rodinou vs. být s telefonem

Why is lepší the same form for rodinou and telefonem? Shouldn’t it change for gender?

Here, lepší does not directly agree with rodinou or telefonem. The structure is:

je lepší být s rodinou než s telefonem
- literally: it is better to be with family than with the phone

lepší is in the default (masculine/neuter) form because it goes with an implied to (it):

(To) je lepší. – It is better.

The comparison is between two infinitive phrases:

být s rodinou
(být) s telefonem

You don’t change lepší for those; you keep lepší the same.

Why is there only one být? Why not …být s rodinou než být s telefonem?

Both versions are grammatically correct:

Myslím, že je lepší být s rodinou než s telefonem.
Myslím, že je lepší být s rodinou než být s telefonem.

In Czech, if the verb is the same in both parts of a comparison, you can omit it in the second part:

Raději budu doma než v práci.
(than [I’ll be] at work)

Omitting být after než here makes the sentence a bit shorter and more natural in speech, but including it is also fine.

Could I say Myslím, že být s rodinou je lepší než být s telefonem? Is this word order okay?

Yes, that sentence is completely correct and natural:

Myslím, že být s rodinou je lepší než být s telefonem.

Here you have:

být s rodinou as the subject of the clause
je lepší as the predicate

Both word orders are fine, just slightly different in focus:

Myslím, že je lepší být s rodinou než s telefonem.
– It is better to be with family than with the phone.
Myslím, že být s rodinou je lepší než být s telefonem.
– Being with family is better than being with the phone.

Same meaning in practice; both are good to use.