Studying Soil Scientifically

Why do you have so many different bags of dirt?” Chris Studying Soil Scientifically Why do you have so many different bags of dirt?” Chris asked his mother. They had just moved into a new house, and he was helping her put some of their old plants into new pots. “I need to use different soils for different plants,” she said. “Sometimes, I even need to mix together soil from different bags.” “But why don’t you just dig up some dirt from the backyard? There’s plenty back there!” said Chris. “Each plant has its own needs. Look at the difference between the orchids and the cactus plants in the pots over there, Chris,” she said. “Whether they grow inside the house or outside in a garden or a field, all plants need different amounts of light, different amounts of water, and even different soils.” “Different kinds of soil?” asked Chris. “Isn’t all dirt the same?” “Take a look in these bags,” answered his mother. “What do you observe?” • • • Why do plants need soil to grow? What are the differences among soils from different places? In this unit, you will learn how scientists describe and study soil. You will learn what is found in soil and how it helps crops grow.

Every day, people are surrounded by many objects and events. 1Into the Field Every day, people are surrounded by many objects and events. n o Scientists often spend time observing objects and events carefully. t i i In this activity, you will observe objects with a scientist’s eye. n a v e s t i g CHALLENGE How completely can you describe a group of objects? Materials For each group of four students 1 set of objects 1 set of Object Labels For each student 1 Student Sheet 1.1, “Recording Observations”

Procedure analysis Into the Field • Activity 1 Study the set of objects for one minute. After the objects have been removed, write down the names of as many objects as you can remember in Row A of Student Sheet 1.1, “Recording Observations.” Describe them as completely as you can. Discuss your list with the rest of your group. In Row B of Student Sheet 1.1, create a single list that names (or describes) each object your group observed. Have one person from your group get a set of Object Labels from your teacher. With your group, place each label next to the correct object. Compare the labeled objects with your group’s observations in Row B. In the last column of Student Sheet 1.1, record the number of objects that you and your group completely described. Hint: If someone else can identify an object based on your description, it is completely described. In Row C, add the names of any objects that your group did not identify. In Row C, under “Total Number of Objects,” record the number of objects that your group missed. analysis Read your object descriptions again. Select one that you think could be more complete and rewrite it, giving a more complete description of the object. Modern scientists often work together in groups. What are the possible benefits of this? When is it important for scientists to describe objects completely? You are an explorer who has discovered a mountain, which is then named after you. You tell a friend how to get to your mountain. Should you tell your friend the name of the mountain, describe how it looks, or both? Explain.

Key to Analysis Icons Activity 1 • Into the Field Many of the objects you observed are used for measurement. The system of measurement most commonly used in the United States is known as the English system. In most other countries, the metric system is more commonly used. Look at the table below. What units are familiar to you? Which of the units below were found on the objects you observed in this activity? Choose three of the units listed below and give an example of something commonly measured with each one. Units of Measurement Common English Units Common Metric Units Length inches, feet, yards, miles centimeters, meters, kilometers Mass ounces, pounds grams, kilograms Volume cups, quarts, gallons milliliters, liters Key to Analysis Icons = Answer the question by yourself. = Discuss with your partner. = Discuss with your group. = Discuss the question in class.