Call the Pakistani cultural center and find out if they offer any kids' programs after school or on the weekend. If the kids are preschoolers, an Urdu day care would be ideal as the kids pick up the language by osmosis.
Speak only Urdu to the kids, if you know the language. If not, hire a native speaker to tutor the kids. Also, ask him to assign homework between the lessons. This homework could be listening to songs for young kids or writing reports for the older ones.
Watch Urdu programs on YouTube. This is an effective way for kids to learn the language, because they do not think of YouTube instruction as being work.
Play Urdu games. Kids in Pakistan play "tag" and "hide-and-seek," just like they do in the United States, but they do it in another language. This is also a good way to teach your kids that cultures share similarities.
Enroll the kids in an Urdu language program where they can learn Persian script. They will learn the characters and how to write from right to left.
Buy Urdu story books for the kids. Have the older kids read to the younger ones and help them understand the Nastaliq script.
Find an honorary grandparent for the kids. Seniors love to tell stories about their childhood, so it is a good way for the kids to pick up Urdu language skills. Ask the grandparent to help the kids with their pronunciation and to correct their grammar mistakes.
Sing Urdu songs and chants from the Quran. Because Urdu is spoken in a Muslim country, the religion is closely tied in with the language and it is not possible to separate them.