Literacy, Non - Fiction Writing.  Activities for children can include writing letters.  As part of KS1 or KS2 children english home work, they can be asked to write a thank you letter.

Teach My kids, worksheets for kids, includes How To Write A Letter.  This writing frame worksheet asks KS1 or KS2 children to write a thank you letter to some carol singers, who have visited your house to sing to you.  Ideas to write a letter are included.