UNIX for Beginners Questions & Answers

I am a student in a UNIX/Linux classes having hard time with grep looking for assistance on some home work

I need to figure out some kind of grep command to get a out put that only gives me information from a sample file and only list the people with the first name John the sample file is named smallFile and contains information like

John:Doe:ECE:3.54:doe@jd.home.org:111.222.3333
James:Davis:ECE:3.71:davis@jd.work.org:111.222.1111
John:Clark:ECE:2.68:clark@xyz.ab.com:111.111.5555
John:Lee:EE:2.64:jlee@j.lee.com:111.111.2222
Lu:John:CS:3.06:lu.john@xyz.org:111.333.1111
Adam:Giles:SS:2.54:giles@cric.org:111.333.3333
Andy:John:EECS:3.98:john@aj.ece.edu:111.333.4444

I came up with
(grep -n '\<John\>' smallFile)
and get

1:John:Doe:ECE:3.54:doe@jd.home.org:111.222.3333
3:John:Clark:ECE:2.68:clark@xyz.ab.com:111.111.5555
4:John:Lee:EE:2.64:jlee@j.lee.com:111.111.2222
5:Lu:John:CS:3.06:lu.john@xyz.org:111.333.1111
8:Andy:John:EECS:3.98:john@aj.ece.edu:111.333.4444

or
(cat smallFile | grep John)
and get

John:Doe:ECE:3.54:doe@jd.home.org:111.222.3333
John:Clark:ECE:2.68:clark@xyz.ab.com:111.111.5555
John:Lee:EE:2.64:jlee@j.lee.com:111.111.2222
Lu:John:CS:3.06:lu.john@xyz.org:111.333.1111
Andy:John:EECS:3.98:john@aj.ece.edu:111.333.4444

what do I need to change to
(grep -n '\<John\>' smallFile)
to get

1:John:Doe:ECE:3.54:doe@jd.home.org:111.222.3333
3:John:Clark:ECE:2.68:clark@xyz.ab.com:111.111.5555
4:John:Lee:EE:2.64:jlee@j.lee.com:111.111.2222