Subject: The children
Transitive Verb: Served
Indirect Object: Them
Direct Object: Food at the table
The sentence is already in a S-TV-IO-DO Form.
The subject, the one that we are talking to is "The children", what did the children do? It's our verb, "Served", then what did "The children served"?, it's our direct object, food at the table, then for whom is "The food at the table that the children served"?, It is our indirect object, "Them"
So The children served food at the table for them,
In S-TV-IO-DO Form is:
The children served them food at the table.
