Overview
This activity was adapted from a TEA activity authored by:
- Sandra Kolb, Education Consultant, Poulsbo, Washington
- Kolene Krysl, Westside Community Schools, Omaha, Nebraska
- Larry Rose, Pleasanton Middle School, Pleasanton, California
- Wendy Slijk, La Costa Canyon High School, San Diego County, California
The original activity can be found at: http://tea.armadaproject.org/activity/kolb/tobesaltyseaiceornottobesaltyseaice_main.html
Objective
This activity was part of preparing students for Independent Science Inquiry Projects, with a focus on identifying variables (independent and dependent), using quantitative measures and writing research and null hypotheses.
Preparation
Ideally begin the activity before a weekend so that students can put their ice cube trays in the freezer for at least 2 days (over the weekend).
Description
Launch: Tell the students that today they will design a mini-experiment to answer the question: "How does the salt content of water affect its ability to freeze?"
Help students identify the Independent Variable for the experiment and determine methods to measure it. [salt content; concentration, mass per volume, etc]
Brainstorm possible Dependent Variables for the experiment [examples may include the amount of ice that melts in 10 minutes, the amount of water that remains after freezing, the strength of the ice that is formed]
Students will need to determine how they will set up the experiment within the parameters. [primarily the number of ice cubes they can make on their part of the tray, the available equipment for measurements and the time that the trays will be in the freezer (one weekend)]
Explore: Let the students 1. Decide their variables (quantitative Dependent Variables are preferred) 2. Record their research hypothesis in their Journals, stating the difference that they think that they will find, and their null hypothesis, stating there will be no difference between groups. 3. Record their procedure. 4. Set up the experiment.
Put the ice cube trays in the freezer for at least 2 days (over the weekend).
When the trays are removed from the freezer, let the students make their observations and take measurements, recording these in their Journals.
Summarize: In their Journal, have students do the following: 1. Describe their results. 2. Make conclusions about what their results show. 3. Compare their results to their research hypothesis and decide if it was supported or unsupported. 4. Suggest how they would do the experiment differently knowing what they know now and/or suggest extensions to the experiment.
Finally, ask the students to decide if they think the ice that formed in their cups is salty or fresh and to describe how they would go about finding this out WITHOUT tasting it.
Credits
Misty Nikula mnikula [at] whatcomdayacademy.org
This program is supported by the National Science Foundation. Any opinions, findings, and conclusions or recommendations expressed by this program are those of the PIs and coordinating team, and do not necessarily reflect the views of the National Science Foundation.