I have a question about the following sentence:

"一起跟他学习下棋"

According to what I have studied so far the simple construction should be the following one:

Subject + 一起 + Verb
Ex. 他们一起学习下棋。

or

Subject + 跟 + subject + 一起 + Verb
他跟他的学生一起学习下棋。
他们俩跟秋老师一起学习下棋。

For this reason I do not recognise the construction used in the original sentence. Is it correct like that as well? If you could find some references that show usage could you please post them together with your reply. Thanks!

P.S.
This is the reference I have found about the 跟...一起 construction.