Here is a good resource for teaching The Lord’s Supper to elementary age children:
Emphasize that The Lord’s Supper is observed by baptized believers in Jesus. It would be quite okay to briefly mention what it means to be baptized (see Baptist Faith & Message, below).
Be sure to use the term “grape juice” or simply “juice” rather than “wine.” FYI, the Bible does not refer to it as juice or wine, but rather cup or fruit of the vine.
Use the translation you normally use in class (ESV, NKJV, HCSB, etc.).
Serve a snack – crackers/cookies and juice (something along the lines of oyster crackers or bite size cookies, etc). Let the snack be snack-time only. Do not review the words of Jesus at the Last Supper while the children eat their snacks. In other words, don’t lead in an “official” observance of The Lord’s Supper, for various reasons (some kids aren’t baptized, some will not understand, and of course many of them are not saved).
Another suggestion is to enlist one of your parents to prepare a breakfast snack of unleavened food and juice (internet search provides plenty of recipes). I’ve done this before with the 6th grade class. The lesson might include how the passover dinner was instituted by God and that it was the Last Supper Jesus had with His disciples. For resourcing on this, click Passover lesson. If you wish to use this, let Dionne Martin or me know and we will prepare your copies (or use the copier on the second floor).
Our Baptist Faith & Message has a brief summary of our faith statement on The Lord’s Supper and Baptism:
VII. Baptism and the Lord’s Supper
Christian baptism is the immersion of a believer in water in the name of the Father, the Son, and the Holy Spirit. It is an act of obedience symbolizing the believer’s faith in a crucified, buried, and risen Savior, the believer’s death to sin, the burial of the old life, and the resurrection to walk in newness of life in Christ Jesus. It is a testimony to his faith in the final resurrection of the dead. Being a church ordinance, it is prerequisite to the privileges of church membership and to the Lord’s Supper.
The Lord’s Supper is a symbolic act of obedience whereby members of the church, through partaking of the bread and the fruit of the vine, memorialize the death of the Redeemer and anticipate His second coming.
Matthew 3:13-17; 26:26-30; 28:19-20; Mark 1:9-11; 14:22-26; Luke 3:21-22; 22:19-20; John 3:23; Acts 2:41-42; 8:35-39; 16:30-33; 20:7; Romans 6:3-5; 1 Corinthians 10:16,21; 11:23-29; Colossians 2:12.