Activity 1: Surface Tension of water
This is the first water lab for the ninth grade physical science class.
Materials needed: plastic cups, pennies (lots), water, and Ivory liquid detergent.
Procedure:
Fill a cup to the very top with water, ask the class how many pennies they can slide in before the
meniscus
breaks. They can work in pairs. Have them do the lab three times and then average. Why?
Now ask them what would happen if they added 5 drops of Ivory liquid to a full cup of water and then dropped in the pennies. (The soap reduces the
surface tension
of the water so that only a few pennies can be dropped in before the meniscus breaks.
Results:
Have them make a chart of their results. and then a bar graph.
Questions:
1. Why do we repeat the experiment and then average the results?
2. Is this a
qualitative
or a
quantitative
experiment? Why?
3. What does it mean in this lab by controlling the
variables
?
Activity 2: Measuring direction and velocity of the Mill River flow
This activity will correlate the tides in New Haven Harbor with the direction and velocity of the water flow in the Mill River. We will use the Orange Street bridge as our reference point.
Finding the
direction
will be easy: just throw a stick in the river and see whether it floats upstream or down. Then check the New Haven Register for the daily tide schedule.
Finding the
velocity
will give students a chance to use some math. Students will mark off a length along the river bank with string — at least 20 meters. Then they will drop in an orange and take the time in seconds that it takes to float from one end of the string to the other. The answer will be in meters/second. This should be run three times and the answers averaged.
Activity 3: Student Survey Sheet of the Mill River.
-
NAME _____ SURVEY STATION _____
-
DATE _____ TIME OF DAY _____
-
WEATHER _____
-
DEPTH OF RIVER (in meters) _____
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VELOCITY OF RIVER FLOW (in meters/second) _____ (do three times and average) _____
-
DOES THE RIVER FLOW UPSTREAM OR DOWNSTREAM _____
-
TIDES (check the New Haven Register) Time of nearest HIGH TIDE _____ Time of nearest LOW TIDE _____
-
DESCRIPTION OF WATER (color, odor, objects floating?) _____
-
WATER TESTS (sample from bridges if possible)
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DISSOLVED OXYGEN (ppm) _____
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TEMPERATURE (°C) _____
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SATURATION OF OXYGEN (percent) _____
-
pH _____
-
CONDUCTIVITY (ppm) _____
-
COMMENTS _____