Any scale using five notes is "pentatonic" ("penta" is Greek for "five"). However, the pentatonic scale which is used in most Western music uses notes which do not have any semitones. A pentatonic scale starting on C will use the notes C,D,E,G,A (the 1st, 2nd, 3rd, 5th and 6th notes of a major scale).. An easy way to find such a pentatonic scale is by using all the black notes of a keyboard.
Using the pentatonic scale is a good way for children to make up their own tunes. It does not matter too much which note is used for the start and the finish, because there is no feeling of a clear key. The notes always sound good when played together.
Many folksongs are pentatonic, or nearly pentatonic. Well-known songs such as "Land of the Silver Birch" or "Auld Lang Syne" are pentatonic tunes.
Classical composers have sometimes used pentatonic scales, especially Claude Debussy. His piano piece La fille aux cheveux de lin has a tune which is pentatonic except for one note. Maurice Ravel used it to write music which sounded Chinese, and in his Mother Goose suite (Ma Mère l'Oye) which sounds like a fairy tale.
pentatonic song: sing out your melody sing out your song sing a petatonic scale starting on lah lah doh ray meh soh lah!