# Drawing to Scale: II

**Name of Corresponding Unit Plan:** Archaeological Documentation

**Grade Level:** 5-12

**Common Core Standards**:

RS9-10. 3. Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text.

M.6.RP.1. Understand the concept of a ratio and use ratio language to describe a ratio relationship between two quantities.

**Content Areas:** Math, Science

**Recommended Length/Duration: **45-60 minute period

**Learning Goals:** Students will learn to use scale to enlarge or reduce images.

**Description/Sequence:**

- Discuss how archeologists frequently need to produce images of very large areas or objects on maps or diagrams. The maps and diagrams are much smaller than the actual objects, so a “scale” drawing must be made. A scale drawing is “similar” to the original in that it has the same proportions between its parts. It is not “congruent” because the image is smaller.
- Describe how scale drawings are expressed in ratios. A drawing that is half the size of the actual object would have a ratio of 1:2 which means that one unit of measure on the drawing is equal to 2 units of measure on the actual object. If an actual object is 30 cm long, its image would be 15 cm long using a 1:2 scale. Using a 1:30 scale, it would be 1 cm long. Discuss how ratios work like fractions.

Large scale drawings (e.g. 1:2, 1:3, 1:50) are usually of small objects or areas. Small scales (e.g. 1:1000, 1:250,000) are usually for maps of large areas. A typical globe of the Earth has a scale of 1:40,000,000. - Have students choose a two dimensional object from the sample collection, something from around the room, or that they bring from home.
- Have them use their ruler and full size grid paper to measure its dimensions.
- Have students draw the outline of their sample on the 1:2 grid on their worksheet.
- Have students further reduce their drawing on the 1:4 grid on their worksheet.
- Informally ask students what parts of measuring their sample are easy or difficult. Discuss how the drawings change as they are reduced.

**Assessments: ** Check worksheets for accuracy.

**Materials/Resources: ** Full-sized grid sheet, Worksheets, Rulers

**Special Considerations: **Scientific measurements are generally easier to take and calculate in metric than in English units. Additional work may be needed if students are not familiar with metric measurements, or if the teacher chooses to use English units.

**Extensions**:

Interested students may want to make a scale drawings of more complicated or three dimensional objects.

Interested students may want to look at house plans, architectural drawings, product plans, and maps to see how they are drawn.

Students may want to try using a scale grid to reduce or enlarge a piece of art, cartoon, or coloring book image.