Hands-on Activity: Density Column Lab - Part 2
Educational Standards :
Pre-Req Knowledge (Return to Contents)
Learning Objectives (Return to Contents)
After this activity, students should be able to:
Materials List (Return to Contents)
Each group needs:
Note: Many of these materials are the same as those used in the associated Part 1 activity; re-use the marbles, crayons and pasta noodles, if still available.)
Introduction/Motivation (Return to Contents)
(Review with students what they did in the associated Density Column Lab – Part 1 activity.) During the first part of our two-part lab activity, we used triple balance beams and graduated cylinders to make density measurements of a few irregularly shaped solid objects. Why did we use the triple beam balance?
What did it help us measure? (Listen to student answers.) That's right; we used the triple beam balance to measure the mass of the objects.
Why did we use the graduated cylinder? What did that help us measure? (Listen to student answers.) The graduated cylinder enabled us to measure the volume of the objects. We did this by measuring the water displacement by adding the objects to a known volume of water and determining the change in total volume.
Why did we measure mass and volume if we really were looking for the density of these objects? (Listen to student answers.) Density is equal to the mass of an object divided by its volume. So we measured mass and volume in order to have the data necessary to calculate density.
Today, we will conduct the second part of our two-part lab activity. In this part, we will expand what we did in Part 1 to include several household liquids and compare them to the densities of the irregularly shaped solid objects. Do you think liquids can have different densities, similar to solid objects? We will find out today and create density columns with three liquids and the four solid items. In addition, we will see what happens when we add detergent to the column. Let's get started!
Vocabulary/Definitions (Return to Contents)
Procedure (Return to Contents)
Note: This lab is meant to be inquiry-based so the worksheet has a loosely written procedure.
Before the Activity
With the Students
Attachments (Return to Contents)
Troubleshooting Tips (Return to Contents)
Start with corn syrup as the first liquid since it is the densest and extremely sticky (and thus hard to transfer to the other graduated cylinder).
Make sure to slowly add the items, one by one, to the column, otherwise the final placement of the pasta and crayon might be altered in the column.
Assessment (Return to Contents)
Part 1 Recap: As a class, have students discuss results and conclusions from the Density Column Lab – Part 1 activity. Talk about misconceptions about mass and density and how that relates to judging the densities of liquids.
Predictions: Direct students to the Density Column Lab – Part 2 Worksheet to rank the liquid test items based on what they believe to be the most and the least dense. Expect most students to use mass to make their assumptions.
Activity Embedded Assessment
What's Going On? While students are conducting the lab, walk around and ask them questions to keep them engaged and on task. Example questions:
Worksheet: Have students complete the worksheet questions and diagrams and hand them in for grading. Review their work to gauge their comprehension of the material.
Wrap-Up: At lab end, bring students together as a class and review their responses to the worksheet. Make sure everyone understands the answers.
Activity Extensions (Return to Contents)
After completing this activity, present the Density & Miscibility lesson, which explains why the liquids did not mix together initially and why they did mix after the addition of the detergent.
References (Return to Contents)
Comparing the density of different liquids: How do the densities of vegetable oil, water and corn syrup help them to form layers in a cup? Published 2007. Activity 7.3, Investigation 7: Density, Inquiry in Action, American Chemical Society. 2007. Last accessed 2010. (Inspiration for this activity) http://www.inquiryinaction.org/pdf/chapter7/7.3_teacher.pdf
ContributorsJessica Ray, Phyllis Balcerzak, Barry Williams
Copyright© 2010 by Washington University in St. Louis
Supporting Program (Return to Contents)GK-12 Program, School of Engineering and Applied Science, Washington University in St. Louis
Acknowledgements (Return to Contents)
This curriculum was developed with support from National Science Foundation GK-12 grant number DGE-0538541. However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government.