In the 2014 Outline for Sharing Time on p. 26, there is a great activity to help teach this hymn. Below is the excerpt: (GAB is Gospel Art Book)
March: “I Stand All Amazed” (Hymns, no. 193)
Divide the children into four groups. Give group 1 GAB
116, and sing the first phrase of the song to them. Discuss it briefly,
and then have them sing it a few times with you. Continue with each
group and each additional phrase (use the following pictures: group 2, GAB 108; group 3, GAB 57; group 4, GAB
56). Sing the whole first verse with each group standing, holding their
picture, and singing their phrase. Invite the groups to switch
pictures, and sing the song again. Repeat until each group has sung each
phrase. Sing the chorus, and ask the children to listen for how many
times you sing the word “wonderful.” Repeat the chorus a few times with
them, and invite them to place their hands over their hearts each time
they sing the word “wonderful.”