Appropriate age group:
Preschool and Younger
Elementary School
Middle School
High School & Beyond

Type of weather:
Rainy

Description:
You need a large box. A cardboard one will do, but a rubbermaid type thing is better. Collect a few of each of the following:

egg cartons
yogurt cups
lids from frozen drink cans
take-out deli containers
fabric remnants
used gift wrap and ribbon
cereal boxes, flattened for space-can be retaped or glued
small corrugated cardboard boxes, ditto
old hats and socks that are too small or have holes
jars and lids
a bag of dry beans or lentils
a bag or box of pasta such as ziti
toilet paper and paper towel rolls
tissue boxes
paper bags
anything else you could reuse before recycling
glue, tape, scissors, markers, foil, twist ties, rubber bands, etc., in a ziploc bag or other container - have this be an extra set of supplies that you don't use for other stuff, so it'll be special

Other comments or suggestions:
With these items you can make masks, put on a play, do science experiments, create gifts, invent games. You can pick a theme yourself, or ask the kids to, or you can say something like, "Take 5 things and see what we can make out of them."

This kind of box is a must for homeschoolers!