Checking the Museum's Water Audio Tour

Inside the Audio-Guide Recording Booth

The science museum is making an audio tour about Earth's water. In a quiet recording booth, student helpers prepare notes for the narrator. Visitors will hear the recording while examining a water display. The recording and display need to use matching numbers. Before anyone records a sentence, the helpers will check its evidence and decide whether it describes water across Earth or a smaller group of water.

The museum's science team supplies a model based on rounded scientific estimates. Imagine dividing all of Earth's water into 10,000 equal units. The units represent shares of water, not buckets collected from different places. A larger number of units means a larger amount of water. Each unit represents one ten-thousandth of Earth's total water. The planning table gives the salt water and fresh water amounts. These are approximate shares, not an exact measurement of water on a particular day.

Fresh water includes water frozen in glaciers and ice sheets, water stored underground, and water in lakes, rivers, and other places. The team also prepares a closer look at the fresh water portion. For this second display, they round the amounts more roughly: 175 units represent frozen fresh water, and 75 units represent fresh water that is not frozen. These are the same-sized units used in the whole-Earth model. Most of the unfrozen fresh water is underground; the rest includes water in lakes, rivers, and other places.

The helpers will first graph salt water and fresh water from the planning table. Later, they will examine a separate graph that divides the fresh water portion into two groups. The narrator needs to identify which collection of water each display includes. A visitor who hears a number without that information might compare the wrong amounts. The helpers will keep the model units consistent, check labels and scales, and use numbers to revise statements that do not match the evidence.