Justin wants to know how much gas his mother will save if he rides his bike to school rather than being driven in the car. For one month, Justin rides his bike to school. Every week, he asked his mother how much gas she put in the car. The next month, Justin had his mother drive him to school. Again, every week he asked her how much gas she put in the car. What could Justin do to improve this experiment?

1. seamount a raised footwall block between normal fault creates this 2. syncline break between rocks where a hanging wall rises relative to a footwall 3. hot spring on rolling hills, this a dip between hills 4. volcanic neck created when a block with hanging walls slips down between normal faults 5. caldera underwater volcano that never reaches above sea level 6. horst natural hot water on earth's surface containing many minerals 7. graben underwater volcano whose top is eroded flat by waves 8. crater less than a mile in diameter; looks like a bowl at the top of a volcano 9. guyot magma that filled the central vent that remains after the volcano has eroded 10. reverse fault over 1 mile in diameter; looks like a bowl over a volcano