Do you have those certain children who don't like to pray out loud? Try this:
Have the children pair off for prayer time. Normally they will chose the child they are most comfortable with - their best friend or someone who lives near them. Instruct them to share one prayer request, one thanks or praise, and the name of one unsaved child they know. Ask them to pray for the requests of the person they are paired with and then rejoin the group for the rest of the teaching time.
After trying this a few times, enlarge the groups to three and then to four. This should help some of the shy children get used to praying in groups. Of course, if the child still does not want to pray out loud in a group, don't force them but make sure to still ask the child to pray for you and others outside of the meeting time.