Songs are fantastic and motivating resources for children.
We can difference between Nursery Rhymes, very good to practice language, and specific songs for teaching contents.

This is a great site with Nursery Rhymes

You can watch the videos with activities and coloring pages on the web http://www.mothergooseclub.com/ 

Or you can watch the videos through the official YouTube Channel https://www.youtube.com/user/MotherGooseClub 

One of the big problems we all face, whether teaching English to children or adults, is maintaining learners’ interest throughout our lessons. Consequently, we often have to be very creative in the techniques we use. What makes music such a great teaching tool is its universal appeal, connecting all cultures and languages. This makes it one of the best and most motivating resources in the classroom, regardless of the age or background of the learner.

This is the introduction of the article by Adam J.Simpson "How to use songs in the English language classroom". He gives tips about planning for the use of songs in class and he also points out "Six steps for making a song the focus of your class". Very useful to make your English lessons memorable for the students.

Another interesting site where you can find songs for teaching and much more is 

Here are some tips and ideas on how to use the LearnEnglish Kids website for listening practice with your classes.

SONGS FOR TEACHING

One of the big problems we all face, whether teaching English to children or adults, is maintaining learners’ interest throughout our lessons. Consequently, we often have to be very creative in the techniques we use. What makes music such a great teaching tool is its universal appeal, connecting all cultures and languages. This makes it one of the best and most motivating resources in the classroom, regardless of the age or background of the learner. (Adam J. Simpson)

If you want to enliven your lessons in English and other subjects in English, the best way to do it is teaching songs.

Songs are the best resource to adapt the contents to your students and make things memorable and significant.

Whether you teach language or other subject contents through English, it's funny to invent your own songs with different topics. But if you don't have the time to do it, the following website gives you all kinds of songs to teach a variety of topics.

All topics (holidays, special education, skills), all subjects and contents (Science, Arts, Social Sciences...) anything you need for your lessons, you can teach it through songs.

And, if you need extra help or inspiration on how to introduce songs and music in the classroom, there are lots of articles in "Articles and teaching tips" section.

Have fun exploiting and exploring this fantastic resource that makes teaching more enjoyable.