How Heavy?

The purpose of this task is for students to measure the mass of objects with a balance scale. It would be worthwhile measuring the mass of the same object with a different units as well so that students understand that if you use a smaller unit, you will need more of them to equal the same mass. Students should follow up this measuring activity with finding the mass of an object with a scale that gives the mass as a numeric value, such as a kitchen scale. At some point, students should measure the mass of objects that are close to 1 gram or 1 kilogram so they can develop intuition for these units, and they should understand that if a book has a mass of approximately 1 kg, then it will take about 30 books to balance with a 30-kilogram child on an appropriately sized balance scale.