Fourth-graders composing music. The Orff xylophone is often used in teaching music to children because it has removable bars that allow the teacher to present different options to the students. An education researcher used the Orff xylophone to examine the effect of tonality (pentatonic or harmonic minor) and number of xylophone bars (5 or 10) on the ability of fourth-graders to compose melodies that they could play repeatedly.

(a) Twelve children were randomly assigned to each combination of tonality and bar count. Give the two-way layout for this experiment.

(b) Judges listened to tapes of the children's work and assigned scores for several aspects of the melodies. One response variable measured the extent to which children generated new musical ideas in consecutive 5-second intervals of their melodies. Here is the two-way ANOVA table for this variable (the publication does not give the group means):

Comment on the significance of main effects and interaction. Then make a recommendation for teachers who want to use the Orff xylophone to encourage children to generate melodies with new musical ideas.