While there were no statistical differences in parents ' post-test understanding between the TF and IP groups , children in the IP group had significantly greater post-test understanding compared with children in the TF group ( 11.65 ( 4.1 ) vs 8.85 ( 4.1 ) ( 2.8 , 1.4 , 4.2 ) 0-18 scale where 18 = complete understanding ) .