Laboratory and Performance Skills
Laboratory and Performance Skills
This domain tests safe and accurate use of lab equipment, map and reference-table skills, and the ability to construct and interpret graphs, profiles, and contour maps.
Core rules and concepts
- Safety: wear goggles, never eat or drink in the lab, waft odors, point heated test tubes away from people, and report spills immediately.
- Measurement: read a graduated cylinder at the bottom of the meniscus for water; tare a balance before massing; keep the thermometer bulb fully submerged; align a ruler at the zero mark.
- Use the exam’s reference tables for constants, equations, charts, and maps. Contour maps use a constant interval; index contours are labeled; hachures indicate depressions.
- On a map scale, convert map distance to real distance using the scale ratio, then convert units.
- Laboratory skills include mineral tests, rock identification, stream-table observations, density determination, and celestial-sphere modeling.
Worked example
A map has a scale of 1:24,000. A distance of 3 cm on the map equals 3 × 24,000 cm = 72,000 cm = 0.72 km on the ground. For a contour interval of 10 m, a point halfway between the 40 m and 50 m contours is about 45 m.
Traps that cost marks
- Reading the top rather than the bottom of the water meniscus.
- Forgetting to tare the balance or zero the ruler.
- Mixing centimeters and kilometers in scale calculations.
- Drawing contour lines that cross, or ignoring hachures that mark depressions.