Extrapolation and Interpolation With Spaghetti
Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required
Categories: Lab Skills and Safety, Measurement and Units
Alternative titles: Using a Line of Best Fit with Spaghetti, Spaghetti Length and Mass Graphing
Summary
Students measure the mass and length of broken pieces of dry spaghetti, plot the data on a graph, and use a line of best fit to predict the mass of unmeasured lengths. This activity introduces the use of graphs for making predictions and demonstrates proportional relationships between variables.
Procedure
- Break spaghetti sticks into various random lengths.
- Measure the length of each piece with a ruler (in millimeters).
- Measure the mass of each piece using a beam or electronic balance.
- Plot the data on a graph with length on the x-axis and mass on the y-axis.
- Draw a straight line of best fit through the data points.
- Select a length not directly measured (within the range of the graph for interpolation, or outside of the range of the graph for extrapolation), mark it on the x-axis, and use the graph to predict its mass.
- Break a fourth spaghetti stick to that length, measure its mass, and compare the actual value with your prediction.
Links
Graphing Data from Spaghetti Mass vs Length Investigation - Suzie “Fedsie” Feodoroff:
📄 Spaghetti Graphing Activity - mychemistryclass.net: https://www.mychemistryclass.net/Files/1%20Interactive%20Notebook%202011%202012/Unit%200%20Foundations%20in%20Chemistry%20DONE/Graphing/Spaghetti%20Graphing%20Activity%20with%20graph%20paper.pdf
Variations
- Test different brands or types of spaghetti to see if they follow the same mass–length relationship.
- Extend the experiment by comparing thin versus thick pasta shapes (e.g., spaghetti vs. linguine).
- Instead of snapping randomly, cut precise lengths and compare predictions with actual data.
Safety Precautions
- Be cautious when snapping spaghetti as small pieces may fly off.
Questions to Consider
- Why is a line of best fit better than joining the points dot-to-dot? (It smooths out small measurement errors and shows the overall trend more clearly.)
- What is the relationship between length and mass of spaghetti? (They are directly proportional—the longer the piece, the greater the mass.)
- Why might your prediction not match the measured value exactly? (Experimental error, uneven density, or slight inconsistencies in breaking the spaghetti.)
- How could this method be applied to other real-world measurements? (Predicting weight from height, estimating costs from quantities, or scaling recipes.)