今天我學習了漢語第三課。 better add "了“ into your sentence. you can also say 今天我學完了漢語的第三章 今天我學到漢語的第三章。 also means the same as you asked "today, i studied the third chinese lessons.

The correct one is:今天我学了第三节汉语课。Your words means "Today,I'll studay Chinese lesson3" lesson 3= 第三课。It's after "lesson 1" and "lesson 2" on the book. But "the third Chinese lesson"means 第三节汉语课。It's after "the first Chinese lesson",and "the second Chinese lesson" today.

It should be "我的句子对吗？" :) "今天，我学习汉语第三课。" is ok, also for "studied", if you want to emphasize "第三课". If you want to emphasize "studied", you'd better say "今天我学习了汉语第三课", if you want to emphasize "finish", you can also say ""今天我学完了汉语第三课.

第三课是lesson3 或者 chapter3的意思 I studied the third Chinese lesson today 今天我上了第三节汉语课。（这堂汉语课是我上过的第三节汉语课，我之前上过两节/两次汉语课了）