Here are some ideas for collage art with young children.
Children glue different kinds of seeds on paper.
Children first draw an outline of their picture with a black ink pen, then fill it in with sand. They use a glue brush (inexpensive dollar store brush) to paint glue in the area they want a particular color of sand, then sprinkle that color of sand over the glue using their fingertips to pinch the sand. They shake off the excess sand onto a paper plate. Then they can paint on more glue for the next color.
Colored paper was pre-cut into one-inch strips. Children cut the strips into pieces to glue onto a piece of black construction paper to make a mosaic.
Paint Card Mosaic
Paint sample cards were pre-cut into different sizes of squares, rectangles, and triangles for the mosaic pieces. The paint sample cards are free from hardware stores. Children glued the mosaic pieces onto a square of white construction paper to make the mosaic (I recommend a small square, about 6×6 inches). Each child chose a cup of mosaic pieces that were all one color, but of different hues.
Children used several collage materials of their choice from our art center to create a monster mask on a paper plate.