Sample Lessons

NOTE: The format of this file differs from the actual format in the book because of the graphics used in the book, however, the content is the same.

Topographic Investigation

Objective: The students will map the shape of an unknown surface.

Emphasized Skills: Data collection, measurements and the effect of increment size, graphing, problem solving.

Application to the Real World: Ships and river boats need to know the topography of the ground underneath them in order to avoid hitting the bottom.

Materials: Teaching Tank Masking Tape Construction Paper
. Marker Ruler Stiff Wire (Old Hanger)
. Sounding Stick 3/8 Inch Plastic Tubing .
. Graph Paper Colored Pencils .

Graphic of a typical graph and a tank set-up.

Procedure:

1. Advance Preparation:

..... a. Dismantle the tank.

..... b. Slide the wire inside the plastic tubing (they should be about 12 inches long).

..... c. Make a sloping shape with various geological "formations" by bending the wire.

..... d. Put the tank back together with the landscape inside (see diagram).

..... e. Cover the sides of the tank with dark construction paper.

..... f. Place a strip of masking tape on the outside along the top edge of the tank and mark it darkly in two-inch intervals. Mark it lightly (or with another color) in one-inch intervals. Label the two-inch interval marks 0, 2, 4, 6, and 8.

..... g. Make a sounding stick from a dowel by marking the dowel in ½ inch intervals from one end with indelible marker or pen. A clear straw could also be used. Make sure the sounding stick will fit into the tank and that it is long enough to reach the lowest point of the bottom surface.

2. Explain that depths of a river or sea were "sounded" in olden days by dropping a long line into the water and measuring its depth at any given place and that a profile map of the bottom can be drawn using a collection of data points.

3. Provide the materials to the students. Challenge them to construct a profile map on the graph paper by carefully poking down into the concealed tank with the sounding stick. Remind them not to look down into the tank.

4. Have them start a point zero at the top of the tank and slowly lower the sounding stick until it just touches the surface of the plastic tubing bottom. (Ask students why they should not push hard.) Count how many lines deep the landscape is at that point either by subtracting from the total number of lines on the sounding stick or by labeling it in advance. Mark a dot on the graph paper above the zero point with the depth of the stick at that point.

5. Repeat the procedure at 2, 4, 6, and 8 inches.

6. Use a pencil to connect the dots. Discuss the shape of the bottom that they have received from this initial probing.

7. Repeat the procedure, only this time find the depth at every inch across the top of the tank (take soundings at 0, 1, 2, 3, 4, 5, 6, 7, and 8 inches).

Thinking Questions:

....... What difference, if any, did you see between the shape of the landscape using two- inch increments and the shape using one-inch increments?

....... What does this experiment suggest about data collection for scientific accuracy?

....... What practical applications can you think of for this method of measurement?

Teaching notes:

The smaller the increment, the more detailed and true to the real surface the model will be. They could try ½ inch increments for even better results. Another use may be to use sound for the measuring stick and to determine distances by measuring echoes.

River boat captains on the Mississippi River used a sounding method to keep track of the depth of the river. "Mark Twain" was the call when two fathoms (about 12 feet) of water were under the boat. Samuel Clement chose that phrase as his pen name when he wrote Huckleberry Finn and Tom Sawyer.

NOTE: The format of this file differs from the actual format in the book because of the graphics used in the book, however, the content is the same.

Bubbles - Using Controls

Objective: To determine the best amount of glycerin for producing the largest soap bubbles.

Emphasized Skills: Predicting, observing, measuring, experimenting, using controls, calculating areas, graphing data.

Application to the Real World: Soap and detergent producers formulate products differently according to their purpose. Bubble bath requires lots of large, strong bubbles. Laundry detergents try to minimize the bubbles. Using controls and graphing data are common scientific methods.

Materials: Glycerin Water Plastic Cups (small)

Transparency Sheets Water Soluble Markers Tape

Centimeter Graph Paper Flex Straws Medicine Droppers

JOY Liquid Detergent Graduated Cylinder

Procedure:

1. Tape two flex straws together to make one straw approximately 40 centimeters in length.

2. Darken the lines on a piece of centimeter graph paper. Make clear transparency copies of this page and save for future activities.

3. Tape one transparency graph page to one side of the tank.

4. Add 10 mL of water to the tank. A graduated cylinder would be best here, but any measuring device that could give the same amount each time will work.

5. Add two drops of JOY Liquid Detergent.

6. Insert the flex straw and gently blow through the straw to make some bubbles. Try to make the largest bubble that lasts for at least 15 seconds and record its size. What was the diameter of the largest bubble? Record your observations in a table.

7. Using a dropper add one drop of glycerin to the solution and slowly stir with the straw.

8. Repeat steps 6 and 7 until the diameters of the bubbles do not increase.

9. Using your table, graph the diameter of the bubble on the y-axis and the drops of glycerin on the x-axis.

Thinking Questions:

Would your results change if a different amount of water was used?

Would your results change if a different amount of detergent was used?

Why did you continue to use the same solution instead of changing the water and detergent each time?

How many variables are possible in this experiment?

How many variables did you change in this experiment?

Teaching Notes:

The bubbles are formed due to the interactions between detergent molecules. The glycerin strengthens those interactions. You can also try sugar, corn syrup, or other sweeteners to determine their ability to strengthen the detergent interactions.

Since there are three variables in this experiment, but only one (the glycerin) is changing, the students will quickly be able to see the effect of glycerin on bubble size. It is expected that the experiment Bubbles - Trial and Error would be carried out differently after this experience.

NOTE: The format of this file differs from the actual format in the book because of the graphics used in the book, however, the content is the same.

Do Plants Really Use Carbon Dioxide?

Objectives:

To have students observe that plants use carbon dioxide during photosynthesis.

To have students perform an experiment to show that carbon dioxide is used by plants during their food making process.

To have students use controls during scientific investigations.

Materials: Teaching Tanks, Elodea Plants, Water, Funnel, Clay, Straws, Bromthymol Blue

Graphic of the Teaching Tank

Procedure:

1. Set up four teaching tanks, two sets of those depicted above.

2. Fill tanks to about two inches from the top with water that has been allowed to set for about two days. Add 10 drops of the bromthymol blue indicator and mix gently with a stirring rod.

3. Place about 10 Elodea sprigs in two of the tanks using your stirring rod.

4. Tape two plastic straws together to make one long straw. Slide one long straw into each tank next to the hose gasket on one side of the tank until one end of the straw reaches the bottom of the tank.

5. Gently blow through the straws for a few minutes or until the carbon dioxide from your breath turns the blue colored water yellow. A yellow color indicates that carbon dioxide is present. Take some plasticine clay and seal the top of the tanks so that no air can enter. Be sure to seal all of the tanks (even those without plants in them).

6. Place one Elodea tank and one "no plant" tank in "direct sunlight" . Place the other two tanks in a dark room.

Thinking Questions:

What did you observe happen in the tanks that were placed in the sunlight?

Why did the blue color turn clear?

For what purpose were two tanks placed in the dark?

Why were there two tanks without plants?

Teaching Notes:

After about an hour the blue color will reappear in the tank with Elodea plants that are exposed to direct sunlight. When the tanks are sealed with clay, there is no way for the carbon dioxide to escape or be used up, except by the plants. This indicates that carbon dioxide has been used up by the plants during photosynthesis.

No change should take place in the tanks with only water or in the tank with Elodea plants that was placed in the dark. These tanks are being used as "controls" in this experiment. The tanks with only water show that plants are needed and the tank with plants that was put in the dark, shows that light is needed. Since light is needed, it seems likely that photosynthesis is responsible for taking the carbon dioxide from the air.

Bromthymol blue can be used in this situation as an indicator for carbon dioxide. Since our breath has a high concentration of carbon dioxide, when we blow into the tank through the straw we put carbon dioxide into the water. This is indicated by the yellow color. When the plants use enough of the carbon dioxide from the water the color will change back to blue.