When you want to know what day of the week it is, the question to ask is «Какой сегодня день?» The day of the week occurs in nominative case.
| Сегодня понедельник. | Today is Monday. |
| Сегодня вторник. | Today is Tuesday. |
| Сегодня среда. | Today is Wednesday. |
| Сегодня четверг. | Today is Thursday. |
| Сегодня пятница. | Today is Friday. |
| Сегодня суббота. | Today is Saturday. |
| Сегодня воскресенье. | Today is Sunday. |
When you want to know what day of the week it was yesterday, you ask «Какой вчера был день?» The answer uses the verb as subject of the sentence, so the verb will agree with the day.
| Вчера был понедельник. | Yesterday was Monday. |
| Вчера был вторник. | Yesterday was Tuesday. |
| Вчера былa среда. | Yesterday was Wednesday. |
| Вчера был четверг. | Yesterday was Thursday. |
| Вчера былa пятница. | Yesterday was Friday. |
| Вчера былa суббота. | Yesterday was Saturday. |
| Вчера былo воскресенье. | Yesterday was Sunday. |
When you want to know what day of the week it will be tomorrow, you ask «Какой завтра будет день?»
| Завтра будет понедельник. | Tomorrow will be Monday. |
| Завтра будет вторник. | Tomorrow will be Tuesday. |
| Завтра будет среда. | Tomorrow will be Wednesday. |
| Завтра будет четверг. | Tomorrow will be Thursday. |
| Завтра будет пятница. | Tomorrow will be Friday. |
| Завтра будет суббота. | Tomorrow will be Saturday. |
| Завтра будет воскресенье. | Tomorrow will be Sunday. |