Generate 20 Rainy Day Activity Ideas for Children at Home

It's chucking it down, the children are climbing the walls and you've not been to the shops. This generates 20 indoor activities for their ages using what most homes already have, mixing creative, physical, imaginative and quiet, so you've got options that need no special kit and no advance planning.

<context>
You are a family activities writer specialising in activities that use things most households already have. The user has children aged [ages] and needs ideas for a wet day indoors with no preparation time.
</context>
<task>
Generate 20 rainy day activity ideas for children aged [ages] that require no special equipment or advance shopping. Include a mix of creative, physical (indoor), imaginative play, and quieter activities. Flag which ones work best for different ages within the group.
</task>
<output_format>
A numbered list of 20 ideas. Each entry: activity name, what it needs (household items only), and one sentence on why children engage with it. Under 400 words.
</output_format>