Mix water and acrylic paints together in ice cube trays. For younger preschoolers it may be necessary to mix these beforehand, but older preschoolers and early elementary students are capable of mixing their own colors. Place the trays outside or in the freezer until they are frozen solid. This provides a basic lesson in a liquid becoming a solid. Bring the cubes inside and allow the children to use them to paint on heavy paper. The cubes leave behind color as they melt, providing a visual of a solid becoming a liquid.
Not all birds fly south for the winter. Work with the children to set up a place for our avian friends during the coldest days of the year. Coat cardboard tubes in peanut butter and roll these in birdseed. Hang the tubes near a classroom window. Keep child-size binoculars on hand for impromptu bird watching sessions.
Wait for a calm, snowy day. Give each child a heavy piece of black paper and a magnifying glass. Children enjoy catching the falling snowflakes on the paper and studying them with the magnifying glass. The details of each flake stand out clearly on the paper.