Create a T-chart (using chart paper or large construction paper) and give each student 1-2 pictures. Students discuss as a group (or the teacher can lead the discussion) to figure out which objects would be weighed using pounds or ounces. Students then sort their pictures accordingly and glue to the chart. Next, students estimate the approximate weight of each object in pounds or ounces. This activity can also be used for an individual activity for students to complete at their seats - just create a model and have students make their own t-charts in a journal or on a sheet of paper and have them cut and sort the pictures.