May/June 2017 – Vol. 29 No. 7

Clear Straws as Mini-Density Columns

Posted: Tuesday, January 1st, 2013

by Lisa Hegdahl

Even though I received this lab from my Master Teacher 22 years ago, I’ve never seen it presented at any conference or seminar I’ve attended.  The lab itself is a little long for a full write up here, but with the basics, you can develop an activity to suit your needs. This lab uses the skill that we all learned as kids: picking up liquids with a straw.  However, in this activity students pick up two different liquids to check relative density.  In a nutshell:

  • Prepare four solutions of different densities with varying amounts of saturated saltwater and tap water.  One container has only saturated saltwater, one container has only water, one container has half of each, and the last container has ¼ saltwater and ¾ tap water.
  • Color the liquids so they can be identified easily.  (TIP: If you use yellow and blue as two of your colors, don’t use green.  I use red, blue, yellow, and I leave one clear.)

  • Ask students to figure out the order of the relative densities of the liquids from least dense to most dense.  They do so by using their clear straw to pick up one liquid, and then a second liquid.  If the liquids stack neatly on top of each other, students know that the liquid on top is less dense than the liquid below it.  If the liquids mix, they know the liquids were not stacked in the correct order.  Those who collect data carefully should be able to layer all four liquids in their straw.
  • Students can develop their own data tables to record the results of their straw test, or teachers can create one for them.

I like this lab because the supplies are inexpensive, the activity demonstrates the intended concepts, and the students enjoy using their knowledge and investigative skills to determine the relative densities of the liquids.  I’m confident your success with this activity will be as great as mine.

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Written by Lisa Hegdahl

Lisa Hegdahl

Lisa Hegdahl is an 8th-grade science teacher at McCaffrey Middle School in Galt, CA and is Past-President of CSTA.

2 Responses

  1. Lisa, thank you for this great idea. I love that it is concise, clear and you are right, just the idea is enough to then tailor this for my own students. I’ve lifted it with a credit to you under the title. Sue (8th grade science, Orinda Intermediate School)

  2. I am definitely using this next year as an intro lesson for scientific method and problem solving. Thanks for a great problem solving exercise for my freshmen.

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CSTA Annual Conference Early Bird Rates End July 14

Posted: Wednesday, July 12th, 2017

by Jessica Sawko

Teachers engaged in workshop activity

Teachers engaging in hands-on learning during a workshop at the 2016 CSTA conference.

Don’t miss your chance to register at the early bird rate for the 2017 CSTA Conference – the early-bird rate closes July 14. Need ideas on how to secure funding for your participation? Visit our website for suggestions, a budget planning tool, and downloadable justification letter to share with your admin. Want to take advantage of the early rate – but know your district will pay eventually? Register online today and CSTA will reimburse you when we receive payment from your district/employer. (For more information on how that works contact Zi Stair in the office for details – 916-979-7004 or zi@cascience.org.)

New Information Now Available On-line:

Written by California Science Teachers Association

California Science Teachers Association

CSTA represents science educators statewide—in every science discipline at every grade level, Kindergarten through University.

Goodbye Outgoing and Welcome Incoming CSTA Board Members

Posted: Wednesday, July 12th, 2017

Jill Grace

Jill Grace, CSTA President, 2017-2019

On July 1, 2017 five CSTA members concluded their service and four new board members joined the ranks of the CSTA Board of Directors. CSTA is so grateful for all the volunteer board of directors who contribute hours upon hours of time and energy to advance the work of the association. At the June 3 board meeting, CSTA was able to say goodbye to the outgoing board members and welcome the incoming members.

This new year also brings with it a new president for CSTA. As of July 1, 2017 Jill Grace is the president of the California Science Teachers Association. Jill is a graduate of California State University, Long Beach, a former middle school science teacher, and is currently a Regional Director with the K-12 Alliance @ WestEd where she works with California NGSS K-8 Early Implementation Initiative districts and charter networks in the San Diego area.

Outgoing Board Members

  • Laura Henriques (President-Elect: 2011 – 2013, President: 2013 – 2015, Past President: 2015 – 2017)
  • Valerie Joyner (Region 1 Director: 2009 – 2013, Primary Director: 2013 – 2017)
  • Mary Whaley (Informal Science Education Director: 2013 – 2017)
  • Sue Campbell (Middle School/Jr. High Director: 2015 – 2017)
  • Marcus Tessier (2-Year College Director: 2015 – 2017)

Learn More…

Written by California Science Teachers Association

California Science Teachers Association

CSTA represents science educators statewide—in every science discipline at every grade level, Kindergarten through University.

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Posted: Wednesday, July 12th, 2017

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Written by NGSS Early Implementer

NGSS Early Implementer

In 2015 CSTA began to publish a series of articles written by teachers participating in the California NGSS k-8 Early Implementation Initiative. This article was written by an educator(s) participating in the initiative. CSTA thanks them for their contributions and for sharing their experience with the science teaching community.

State Schools Chief Tom Torlakson Unveils Updated Recommended Literature List

Posted: Wednesday, July 12th, 2017

SACRAMENTO—State Superintendent of Public Instruction Tom Torlakson unveiled an addition of 285 award-winning titles to the Recommended Literature: Prekindergarten Through Grade Twelve list.

“The books our students read help broaden their perspectives, enhance their knowledge, and fire their imaginations,” Torlakson said. “The addition of these award-winning titles represents the state’s continued commitment to the interests and engagement of California’s young readers.”

The Recommended Literature: Prekindergarten Through Grade Twelve list is a collection of more than 8,000 titles of recommended reading for children and adolescents. Reflecting contemporary and classic titles, including California authors, this online list provides an exciting range of literature that students should be reading at school and for pleasure. Works include fiction, nonfiction, poetry, and drama to provide for a variety of tastes, interests, and abilities. Learn More…

Written by Guest Contributor

From time to time CSTA receives contributions from guest contributors. The opinions and views expressed by these contributors are not necessarily those of CSTA. By publishing these articles CSTA does not make any endorsements or statements of support of the author or their contribution, either explicit or implicit. All links to outside sources are subject to CSTA’s Disclaimer Policy: http://www.classroomscience.org/disclaimer.

Teaching Science in the Time of Alternative Facts – Why NGSS Can Help (somewhat)

Posted: Wednesday, July 12th, 2017

by Peter A’Hearn

The father of one of my students gave me a book: In the Beginning: Compelling Evidence for Creation and the Flood by Walt Brown, Ph. D. He had heard that I was teaching Plate Tectonics and wanted me to consider another perspective. The book offered the idea that the evidence for plate tectonics could be better understood if we considered the idea that beneath the continent of Pangaea was a huge underground layer of water that suddenly burst forth from a rift between the now continents of Africa and South America. The waters shot up and the continents hydroplaned apart on the water layer to their current positions. The force of the movement pushed up great mountain ranges which are still settling to this day, resulting in earthquakes along the margins of continents. This had happened about 6,000 years ago and created a great worldwide flood. Learn More…

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Written by Peter AHearn

Peter AHearn

Peter A’Hearn is the Region 4 Director for CSTA.