sorting rocks-light-medium-heavy and orange, white, gray and brown. Extend with: comparisons: bigger than, heavier than, musch smaller than and use the > < symbols to compare while weighing or balancing
Mix grass seed in with potting soil. Fill up a nylon. Tie into segments with string to make a 'caterpillar." Soak in water till saturated. Then let the kids spray it with water every day after and watch it grow. When the grass gets "too long" let the kids give it a "haircut."