Explain to the children that one of the words that start with the letter M is marble. Let them hold and feel some marbles. Then take a shallow box (the lid to a copy paper box works nicely) and tape a piece of paper in the bottom. Squirt a few colors of paint in the corners of the box and drop in a few marbles. Let the children tilt the box back and forth so the marbles roll through the paint and onto the paper. Remind the children as they paint that marble starts with the letter M. Sometimes the children shake the box too hard and the marbles pop out, so make sure they are standing on a surface that can be cleaned easily.
Tell the children that another word that starts with the letter M is magnet. Lay a sheet of paper on a cafeteria tray. Dip a few metal objects such as paper clips into paint and put them on top of the paper. Have the children hold a large magnet under the tray and move it around. The metal objects should follow the magnet and leave a trail on the paper. If your metal objects have too much paint on them they might get stuck and not move, so shake off excess paint before putting them on the paper.
Draw a large block letter M on a piece of construction paper. Give the children bottles of school glue to affix to the letter things that start with the letter M. Some ideas include play money, marshmallows, M&M candies, macaroni noodles and cutouts of moons and musical notes. While the children are gluing, keep reminding them about the letter M, the sound it makes and that the objects they are gluing all start with the letter M.
Give each child a cupful of miniature and large marshmallows and a handful of toothpicks. Let them use these materials to build whatever they can imagine. Some children might need help getting started; others will immediately get the idea and begin building elaborate structures. If the children need help, model a few ideas before they begin. Show them how to make the letter M.