Monday, October 20, 2008 - Block 4B

Redo of last Tuesday's class.

Students took out notebooks
Date 10/20/08
Measuring Liguid Volumes
Went over Content Objectives:
Students will be able to:
a. Correctly identify a graduated cylinder, beaker, pipette
b. Observe a meniscus and correctly measure volumes at the base of the meniscus
c. Make accurate measurements of the volume of liquids in ml using a graduated cylinder.

We use graduated cylinders to accurately measure volumes of liquids. They are called graduated because of all the grades or markings, and they are cylindrical in shape. A beaker does not have fine enough markings and will not give as accurate value for the volume.

Graduated cylinders read in milliliters. 1 milliliter = 1/1000 liter = 1 cc

If you pour liquid in the graduated cylinder, it often does not lie flat, there is often a dip called the meniscus. This is caused because the water is more attracted to the glass than itself. To accurately read the volume, you need to look straight on and read at the bottom of the meniscus.

Drew lots of pictures, eyeball on, bottom of meniscus.

Drew portions of three different graduated cylinders on board, one with markings very 0.1 ml, another with markings every 0.2 ml, and the last with markings every 1 ml. Drew the meniscus and had students figure out what reading it would be.

Explained the plan of the day.
First activity - worksheet on reading graduated cylinders. I made up a new one for this class. Students worked on it and when they finished, had it checked. If any were wrong in a column, I had them check that column (on later tries I may have told them which one to check). After they had them all correct and signed off, they went to next activity.

Activity 2: I set up three different graduated cylinders and put different amounts of water in them. Students had to read the volumes, write them on the back of their worksheet, and get them checked. If they were incorrect, they had to do them over.

Activity 3: Rainbow lab with new lab sheet.

Wrote all activities on board:
1. Complete worksheet and get it checked and signed
2. Read and record measurements of the three liquids: red, yellow, blue. Get measurements checked.
3. Do measuring lab (rainbow lab). Get checked off when done.
r. Measure and record volume and color in each test tube. Provided a few 25 ml graduated cylinders to make things easier otherwise they had to use their 10 ml grad cyl.
5. After measuring, dump liquids down the sink.
6. Rinse out test tubes and pipette
7. Return box with: test tube rack, 6 test tubes, pipette, 10 ml grad cyl, cup
Explained the activities of the day.

Several students did not get the desired results so I had them redo the lab if there was time.

Class went well. Several students finished early.