Lesson 2: Data and Measurement
Engineering decisions must be based on data, not guesses. Learning to collect, analyze, and communicate data accurately is one of the most valuable skills an engineer can have.
Key Concepts
Accuracy and Precision
Accuracy means how close your measurement is to the true value. Precision means how repeatable your measurements are. A scale might always read 1kg too heavy — that is precise but not accurate. Random errors are not precise. You want both!
Units and Significant Figures
Always include units with measurements (5 meters, not just 5). Significant figures show how precise a measurement is. 3.14 has 3 significant figures. 3.14159 has 6. Never report more significant figures than your instrument can actually measure.
Graphs and Data Visualization
A line graph shows change over time. A bar chart compares categories. A scatter plot shows correlation between two variables. Choosing the right graph type is as important as collecting good data.
🆕 Measurement Simulator
Measure the rod with instruments of different precision. See how accuracy and precision affect results!
✅ Check Your Understanding
1. What is the difference between accuracy and precision?
2. Why must measurements always include units?
3. Which graph type best shows change over time?