Mystery Metal Objects
Diagram 1.
Source: https://worksheeteiturgassgbv.z14.web.core.windows.net/types-of-metals-chart.html
Phenomenon
Students are given three small gray cylinders that look almost identical, but each is made of a different material. By observing and measuring properties - mass, volume, magnetism, color - they can identify what each cylinder is most likely made of.
Students ask:
If the objects look the same, how can we figure out what they’re made of?
This investigation builds evidence that materials can be identified by their observable and measurable properties.
Different materials have different properties, even when they look similar. A metal like aluminum is lightweight and not magnetic. Steel is heavier and strongly magnetic. Brass has a yellowish shine and is heavier than aluminum, but it is not magnetic. By observing and measuring properties, scientists can identify materials without needing labels.
When students receive the three mystery cylinders, they can start by comparing appearance. All three look gray at first, but careful observation may show slightly different colors or shine. Measuring mass gives more useful information: heavier objects usually contain denser materials. By measuring volume (such as by water displacement), students can calculate density using mass ÷ volume, a key property that differs between metals.
Another important test is magnetism. Some metals attract magnets, while others do not. By combining these observations, students can match each cylinder to a likely material.
These methods show that objects can be identified by their properties, not just by how they look. Scientists rely on these same methods when studying unknown materials.
Table 1.
Cylinder | Mass (g) | Volume (cm$^3$) | Magnetic | Color/Shine | Density (g/cm$^3$) |
|---|
A | 27 | 10 | No | Dull gray | 2.7 |
B | 78 | 10 | Yes | Bright gray | 7.8 |
C | 85 | 10 | No | Yellow-gray | 8.5 |
Graph of Information - Figure 1.

Table 2.
Material | Density (g/cm$^3$) | Magnetic | Color/Shine |
|---|
Aluminum | 2.7 | No | Dull gray |
Steel | 7.8 | Yes | Bright gray |
Brass | 8.5 | No | Yellowish shine |
Graph of Information - Figure 2.
