Only Lutherans, on the basis of the Bible, believe that the Word and the Sacraments are means of grace, ways by which God comes to us. For example Rom. Prayer is not called a means of grace. The means of grace bring us forgiveness of sins and salvation. Prayer is an exercise of faith, a response of the Christian to God.
Parents feed their children daily bread.
The children respond by speaking to their parents. Because the Lord's Prayer is the model prayer in which Jesus enumerates all our needs, Luther made it one of the chief parts of both the Small and the Large Catechism. Before you preach on Luke 11 read again pp. 17-20 in the Russian Lutheran Catechism. Evidently, Jesus taught the Lord's Prayer often but did not always use the same form.