Do Rocks Absorb Water?

Posted by David Wetzel

Porous Sandstone Rock

Although it is not obvious to the casual observer, rocks absorb water. You can ask your students to observe rocks all day long and they will not be able to tell if the rocks they are observing are absorbing water. However, there is an investigation which allows students to discover that rocks absorb water and how much water specific rocks absorb.

Porous rocks are the best to use for this investigation; however, these rocks are not always available. The best porous rocks are: sandstone, limestone, shale, and granite. If these rocks are not available then a common brick from any home improvement store will work. Bricks are made from same materials found in porous rocks.

Do Rocks Absorb Water Investigation

Materials - per group: large plastic container, large beaker or measuring cup, one brick, water, scale

Procedures -

1. Weigh your brick
2. Place brick in the plastic container
3. Measure the exact amount of water poured into container (ensure brick is completely covered with water)
4. Leave the brick in the container for 30 minutes
5. Remove brick from water and allow all excess water to drain off brick back into container
6. Measure the amount of water remaining in the container
7. Weigh your brick after it has been the water for 30 minutes
8. Ask students questions (see next section)
9. Using the chalk board, overhead, or graphing software projected onto screen create class graph of findings

Ask Students the Following Questions -

1. Did your brick absorb water?
2. What evidence do you have to support your observation?
3. How much water did your brick absorb?
4. What is difference in weight of your brick following the investigation?
5. Additional questioning ideas can be found at 20 Questions to Ask Students in Science Projects

Extension -

1. Allow bricks to soak overnight, then collect data
2. Measure how much water a sandstone rock, limestone rock, and shale rock absorb
3. Students graph the findings using bricks, limestone, sandstone, and shale - labeling dependent and independent variables
4. Ask students which rocks are more or less resistant to weathering.

Resources

Students - Water Science for Schools by US Geological Society

Students - Erosion

Teacher - Understanding Scientific Inquiry

Teacher - Writing in Science

Solar to Heat Energy Transformation Investigation

Posted by David Wetzel

Solar Energy Transformation

Simple demonstrations of solar to energy transformations allow students to investigate energy transformations into other types of energy. Examples include: solar to heat, solar to electrical, chemical to electrical to mechanical, mechanical to electrical to heat, etc.

The following investigation is safe for students to study energy transformations.

Solar to Electrical to Heat Energy Transformations

The image demonstrates solar energy being transformed into electrical energy (solar panels). The electrical energy is then transformed to heat energy as it heats the water in the tank (red color in in tank indicates cold water transformed to hot water by electrical heating strips in the bottom of the tank).

This can be investigated in the classroom by doing the following:

Materials -

Small solar panel, thermometer, small beaker or clear cup, water, and 1.5 feet of non-insulted wire, bright flashlight (if do not have access to sunny window)

Introduction -

Hold a class discussion about energy transformations: however, do not focus specifically on the transformations in this investigation. The discussion needs to be on all types of energy transformations, allowing the students to guide the discussion and share what they know in advance from prior knowledge and experiences (PKE).

Procedures -

1. Fill beaker half full of water
2. Measure the temperature of the water with the thermometer and leave thermometer in water
3. Connect each end of the non-insulated wire to the solar panel
4. Coil the looped end of the non-insulated wire four times and place into water
5. Shine bright flashlight (or sun light) on solar panel
6. Record the temperature of the water over a period of several minutes

Sample Questions to Ask Students -

• Ask students to explain what happened and evidence to support their explanation.
• What type of energy transformations occurred and their evidence to support their answer.
• Ask students how or where their findings in this investigation influenced by their PKE.
• Ask students to explain any examples of potential and/or kinetic energy.

Options -

• Students form a hypothesis based on PKE.
• Students measure time of temperature changes with a stop watch.
• Students draw a graph of the temperature changes - indicating independent and dependent variables.
• Students explain control and uncontrolled variables.

Resources

The following resources can be used to support this investigation:

Understanding Scientific Inquiry

20 Questions to Ask Students in Science Projects

Writing in Science

FT Exploring Energy Transformations

How to Build a Rain Gauge

Posted by David Wetzel

Rain Gauge

The primary moisture sources in the United States are the Atlantic and Pacific Oceans as well as the Gulf of Mexico. Winds around high- and low-pressure systems transport this moisture inland.

Once the moisture is in place, clouds still need to form. The most effective way for this to occur is for the air to be lifted. This is accomplished by forcing the air up and over mountains or, more commonly, by forcing air to rise near fronts and low-pressure areas.

Cloud droplets and ice crystals are too small and too light to fall to the ground as precipitation. So there must be processes through which cloud water, or ice, can grow large enough to fall as precipitation. One process is called the collision-and-coalescence or warm-rain process. In this process, collisions occur between cloud droplets of varying size, with their different fall speeds, sticking together or coalescing, forming larger drops.

Follow the instructions below to create your own rain gauge.

Materials

• Straight-sided glass or plastic container, with a diameter of about two inches or less (such as an olive jar)
• Coat hanger or wire bent to make a holding rack
• Measuring spoons: 1 teaspoon and 1/4 teaspoon
• Hammer and nails to secure the rack
• Felt tip marker

Procedure

1. Rain gauges measure the amount of rainfall in cubic inches. So your first task is to make a scale for your container that shows how many cubic inches of water are in the container. One cubic inch of water is about 3 1/4 teaspoons, so you can draw the scale on your container by pouring 3 1/4 teaspoons of water into your container, then drawing a short line at the level of the water. If you look closely, the top of the water will seem to be slightly curved and thickened. Draw your line so that it matches the bottom of the curved surface (which is called a meniscus). This line corresponds to a rainfall of one inch.
2. Add another 3 1/4 teaspoons of water to the container and draw another line. The second line corresponds to a rainfall of two inches.
3. Repeat Step 2 until you have at least five marks on the container. This will be enough for most rain events, but you may want to add another line or two - just in case!
4. Find a location for your rain gauge where there is nothing overhead (such as trees or a building roof) that could direct water into or away from your gauge. The edge of a fence away from buildings is often a good spot. Another possibility is to attach your rain gauge to a broomstick driven into the ground in an open area. Be sure to record rainfall soon after a rain event to avoid false readings caused by evaporation.