Tell students that today they are becoming astronomers. They are exploring space and have discovered a new planet. Students will get to create their own planets. They must draw a picture of their planet. Tell students that they must include the characteristics of a planet, which you listed above. They must decide where in the solar system their planet will be located.
Give them other choices about what to include with their planets. Allow them to decide whether their planet will support life, have water, what kind of gravitational pull it will have. Remind them the gravitational pull has to do where their planet is in relation to the sun.
Create a rubric together as a class that has five categories, with each category worth twenty points. Some category suggestions include grading on accuracy, presentation, staying on task, and neatness.
Pass out the construction paper, crayons, and markers. Have students create a poster of their planet. You can also have students use modeling clay to make a model of their planet instead and write up a description of their planet.