In this activity, students use scale, proportion and/or ratios to develop a scale solar system calculator. Using spreadsheet software, students will determine the size of and/or distances between planets on a solar system model that fits on a playground. Materials Example not-to-scale images of the solar system Computer or mobile device Spreadsheet software (e.g., Excel or Sheets) Distance markers (cones, ground stakes, etc.) Paper Pencil, pen and/or colored pencils Ruler with centimeter markin