How to Predict an Outcome Based on Data or Evidence on the GED Science Test

By Murray Shukyn, Achim K. Krull

Using evidence to predict outcomes is a necessary skill for the GED Science test. The greatest benefits of scientific studies can often be attributed to the fact that their conclusions enable people to predict outcomes. (You probably wish science could help you predict your outcome on the test!)

You witness science in action every day you check the weather forecast. By observing barometric pressure, humidity, temperature, the movement of high- and low-pressure systems, and other factors, meteorologists can make reasonable predictions about future weather conditions.

In a similar way, the Science test presents you with scientific information and asks you to predict outcomes based on that information. Here are a couple sample questions to help you practice answering such questions:

This graph shows the effect that adding salt to water has on water’s melting and boiling points. One teaspoon of salt is 6 grams, and 1 kilogram of water is approximately 1 quart.

The effect that adding salt to water has on water's melting an boiling points.

  1. John adds 3 teaspoons of salt (NaCl) to a 6-quart pot of water to boil it at 105° Celsius instead of at the 100° Celsius he is accustomed to, because he read online that adding salt to water increases its boiling point. One teaspoon holds about 6 grams of salt. Did he add enough salt? Yes or No: _______________

  2. A certain plant species can have curly or flat leaves. The allele (gene form) for curly leaves is dominant, and the one for flat leaves is recessive. Two plants of the species are crossed, both with curly leaves. The Punnett square for the breeding looks like this, with “C” representing the allele for curly leaves and “c” representing the allele for flat leaves:

    A Punnett square for a breeding.

    What percentage of the offspring is likely to have flat leaves?

    • (A) 0%

    • (B) 25%

    • (C) 50%

    • (D) 75%

Check your answers:

  1. No. According to the chart, John would need to add more than 250 grams of salt to the water to raise its boiling point 5° Celsius. That’s more than 41 teaspoons of salt! You may have to do a little math in your head to answer this question.

  2. Only 25% of the offspring would be expected to have flat leaves. Because “C” represents the dominant gene, both “CC” and “Cc” offspring would have curly leaves. Only “cc” offspring would have flat leaves.