Play "Finger Puppet Conversations"
By now, everyone should have the idea of the structures from the song, so we are going to have some fun role-plays with the finger puppets. First model with one child. Hold up one finger puppet (e.g. mother) and get the other child to hold up one finger (e.g. grandfather). Role-play a fun conversation, for example:

T: Hello grandfather.

S: Hello mother.
T: How are you?
S: I'm fine, thank you. How are you?
T: I'm fine, thank you. See you soon.
S: See you soon.

Then you can change finger puppets and do the conversation again. Depending on level, you can also throw in a few more questions, such as, "What's your name?", "How old are you?", "Where do you live?", etc. Now the class can role-play. Put everyone into pairs and set a timer to one minute. Shout "Start!" and the pairs should role-play with different puppets until the timer goes off. Then shout "Change partners!" and everyone finds a new partner for another one-minute conversation. Keep going for a few rounds.