PBL Inquiry Lesson

Which Salt(s) Should Be Used On The Roads During Inclement Weather?

Overall Information:

Project Based Learning, PBL's, need to be content based, relevant, and provide a real work atmosphere.

Content—The students will demonstrate their understanding of freezing point depression and how different ionic salts can be used in the winter months to prevent roads and parking lots freezing.
Relevance—Students will use their scientific knowledge and experimental findings to help predict which products the city/county should use to prevent surface freezing in our community during the winter.
Real Work— Students will present to city and county road maintenance employees their findings from experimentation and research of which ionic salt is best to distribute on the roads during hazardous winter weather.

Phenomenon:

Show this video to students:

https://www.youtube.com/watch?v=8Ab4TTXUDY8

Questions:

Allow students to ask questions about the video. Students will record their questions on a Google Doc.

Provide them the teacher question as well: "Which Salt(s) Should Be Used On The Roads During Inclement Weather?" Each group is hired as science consultants by our local road department to help them decide which salt(s) should be used.

Investigation:

Students are put into groups of 6. Within each group, the students are broken up into pairs. Each pair researches one salt (Sodium Chloride, Calcium Chloride, or Aluminum Chloride) and will report back their findings to their peers.

Part 1: Each pair had to determine the freezing point using the following basic procedure:

FREEZING POINT LAB

Part 2: Students had to research information on their salt and record their findings in a shared Google Sheets.

Winter Salt Research Project

Part 3: Reflection Conversation

Protocol for group table discussion

Each pair takes 6-8 mins to discuss their findings with each other and decide on what they will use as their talking points.
TABLE DISCUSSION BEGINS. Assign a timer. This person cannot be talking but must use their phone to set the timer on stopwatch.
1. Each pair has 3 mins to discuss their salt. The experimental results and the research. Students should use their chromebooks to actually show their results in their discussion. While one pair is talking, the other members are only listening and taking notes. Once the three minutes is up, the next pair goes. Do this until all three pairs have shared their information.
2. Take the last 6 mins to discuss/rank the salts as best to use for the road department. Also, in this 6 mins, discuss what further lab procedures you as a group want to do if any. For example, mixtures. If so, what type of ratios?

Task:

Gather your information and prepare a presentation that you will present to the city and county road maintenance employees your findings from experimentation and research of which ionic salt(s) is/are best to distribute on the roads during hazardous winter weather.

Annotation:

This PBL experience was great for the students to experience. Not only did they utilize content knowledge, but the information we learned was important for our community, and the tasks they performed was real work. This larger project was eleven days total where students accessed prior knowledge, performed both laboratory and online investigations, participated in scientific discourse, made meaningful decisions, and presented their findings to pertinent professionals in our community.

Each group of students (6-7) divided into pairs and chose 1 of 3 salts (NaCl, CaCl₂, or AlCl₃) to study in the lab and do online research to determine cost and environmental impact on roads and the community. Once given the salts, students experimented to collect FP data for the aqueous salt solutions. The students collected data using Vernier temperature probes connected to their Chromebooks using a data collection app called Graphical Analysis. The students recorded their research in a Google Sheet (for their lab book) where they could share their work. Once completed their work, the pairs returned to the large group to reflect and deliberate on each salt in order to recommend one to the road department. The students followed a protocol that I developed. As each pair shared their information, I walked around to each group ensuring all students were sharing. Finally, the students took a couple days to develop their presentation so they could recommend their salt to our local road department officials.

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