I allowed my students to choose between two separation type laboratories. About two thirds of the class chose to separate the flavoring out of a grape of cherry soda. The rest of the students used paper chromatography to determine if red-40 dye was in a specific type of candy.
Laboratory Assessments and Resources
As I began to prepare my labs for this upcoming year, I decided to put a bit of a twist on a previous density of a block lab I had used in the past entitled the Measurement Challenge that is sold by Flinn Scientific. It can also be used to find the mass of a block given the materials density and requiring students to measure and calculate the blocks volume. My added twist resulted in great scientific discourse.
Near the end of the school year we are all thinking about what we will do with our AP Chem students until the end of the semester. Last year I wrote about a post AP independent study activity that I use dealing with transition metal compounds. I still like it and use it. But this year I want to talk about a very involved lab that many of my colleagues are ignoring.
I tend to enjoy acid base titrations for several reasons. First, students get to work with burettes, acids, bases and they see a nice "color change" when they reach an endpoint. Many times, students who tend to struggle with pen and paper testing excel at the "hands-on" approach. Titrations also dovetail well with stoichiometry which provides a nice review of information closer to the end of the year.
To assist in grading the lab results for this and other quantitative labs that we did, I created Excel spreadsheets where the students’ results could be entered. The spreadsheet then did all the required calculations and compared the students’ results to the theoretical value. This made grading the lab reports much quicker and more accurate, flagged incorrect student calculations, allowed a much more complete discussion of the lab results and permitted “what if” questions to be discussed.
The purpose of a lab practicum is to assess a student’s understanding of the content by completing a hands-on challenge. These assessments focus more on problem-solving skills than technique.
How do teachers encourage building individual lab skills in classes of over 30 students where labs are done in groups of five or six students? My science department collaborates daily, and we have been discussing this concern for a few years now. Many trials and errors have occurred.
I always feel a need to start the year off with an activity that ties in observations and conclusions but I also know that most students have had that in science classes since the early grades. Is there a way to revisit an old topic with a new or more challenging bent?
I have been on a mission lately to make scientists out of my students. I am long past my fears that they are not capable of discovering the world for themselves or that they won’t learn the content if we spend too much time on science practices. What I have to work on now is orchestrating the experience. The pedagogy underlying Modeling Instruction has become the backbone for much of my instruction lately. This method of instruction not only gives my students an engaging, authentic scientific experience but has resulted in deeper content knowledge.
In the lab, students are given a 1.5 gram samples of copper. The copper is taken through a series of five chemical reactions ending with the precipitation of solid copper. After the five reactions, students are asked to return their 1.5 gram samples of copper to the teacher.