## How Much Do You Really Weigh?

### Margaret Bogan PhD

#### Description

Students use a computer to analyze how their weights are affected if the students are placed on various planetary bodies. The students will record their findings on a data sheet.

#### Objectives

The student understands that mass is the amount of material in an object.

The student knows that gravity causes an object to have weight.

#### Materials

-12 X 6 Posterboard placards inscribed with the names of at least 5 planets and the Earth's moon
-Posterboard cut-outs of each planet showing relative size and other physical features of the planets (This can be made or procured at a teacher supply store.)
-Scotch tape to attach placard and planet cut-outs to the table
-Data sheets with an area to record each student's weight on each of the planets to which they are assigned
-At least two bathroom scales
-Several computers with Internet connection for each group of students (Provide a computer for each group of students if possible)

#### Preparations

1. Ensure that you have enough data sheets for each student.
2. Ensure that all computers are in working order and connected and bookmarked to the NASA website http://kids.msfc.nasa.gov/Puzzles/Weight.aspl.

#### Procedures

1. Teach students the concept of mass. Give a definition, an example, and a non-example.

2. Teach the students the concept of weight and how it is dependent on the mass of our planet. Give a definition and several examples.

3. Using the posterboard cut-outs of the various planets, teach the students that the various planets have different sizes and masses.

4. Arrange students in groups of three or four.

5. Inform students that they will use a bathroom scale to measure their weights. (Be alert to any student that may be sensitive about measuring and recording their weight. Such students should be allowed to choose an alternate object or person to weigh, such as their siblings, parents, pets, etc.)

6. First model the activity by showing the students how to weigh themselves and record the weight.

7. The students will measure and record their Earth-weights on the data sheet.

8. Label each work table with a placard indicating a different planetary body.

9. Seat each of the groups at a table and ask the students to imagine that they have been transported to another planet or earth's moon.

10. Ask each student to use the NASA website to calculate their weight on their particular planet. You will need to model this using the site listed in the WebLinks section. The student will record the findings.

11. When each group finishes calculating and recording weights, they rotate to the next table.

12. The lesson is complete when all groups have been to all tables and completed all data sheets.

13. Review key concepts and conduct a guided discussion about the concept of mass, weight, and how the planet's mass affects the weight of the inhabitant.

#### Assessments

The teacher will monitor each group and its members. The teacher will collect and grade the data sheets for completion. The teacher will conduct an informal assessment by asking questions during the discussion period after the group activity. These questions should focus on the students' understanding of mass, weight, and the relationship between planet mass and weight.
The teacher will give the following three-question assessment:
1. What is the term for the amount of matter an object contains?

2. Weight is
(a.) the amount of matter in an object,
(b.) the size of an object,
(c.) the gravitational pull exerted on an object by a planet,
(d.) none of the above.

3. On a planet with more mass than the earth, your weight would
(a.) be the same,
(b.) be more,
(c.) be less

#### Extensions

1. Students write essays on how living on different planets would affect their daily activities.
2. Students calculate their weight if given multiplication factors for the various planetary bodies. Factors are supplied by the teacher. For example, if a student weighs 100 lbs. on earth, on the moon he would weigh 1/6th of that weight. To find his weight, he would multiply his weight by 1/6; 1/6 * 100=16.7 lbs.)