Step 1: Understanding the Question:
The question asks what activity involving building is wished for in the poem.
Step 2: Locating the Information in the Passage:
The last two lines of the poem mention the desired activity.
The poem states: "So you can build a snowman and have / A grand old time." This activity is linked to the hope that school will be out because of the snow.
Step 3: Final Answer:
The poem explicitly mentions the desire to build a snowman as a fun activity to do on a snow day.