Last winter I watched a webinar put on by ACS and AACT called "NGSS in the Chemistry Classroom." As a result of watching that webinar, I took an activity that had NGSS Science & Engineering Practices (SEP) integrated into it and tried it out in class. In this activity, students are required to develop their own procedures and data tables.
It is the time of year that content exams loom large and student stress is high. A few years ago I decided to ditch the typical review packet for something else - an open ended, student led, collaborative concept mapping project and I am never going back to the old way!
There is a traditional stoichiometry lab I have done before. It involves adding dilute hydrochloric acid to sodium bicarbonate, boiling off the fluid and then getting the mass of the sodium chloride. Students then can solve the percent yield for the sodium chloride based on the amount of sodium bicarbonate they use. It is not a bad lab. Something about having hot ceramic watch glasses with acid just makes me a bit nervous. I am not sure where I got this new lab, but it has been one that has evolved over the years It is quick, dirty, relatively simple and uses over the counter (mostly) materials.
Are students reflecting on what their calculated values indicate? This question constantly runs through the minds of chemistry teachers across the country. Recently educators have seen shifts in instruction that promote connections to real-world phenomena using conceptual depth in understanding.
First, I had my students examine the conductivity of a puddle of water the size of a nickel. They checked for conductivity. Then they took a very small amount of sodium carbonate and a fresh puddle of water and pushed in a few crystals from the side. You can still see the crystals in the water but it tested positive for conductivity. They had to explain this. They did the same with a fresh puddle of water and a few crystals of copper (II) sulfate. Again, it tested positive for conductivity but they could still see the blue crystal. Finally, they started again with another fresh puddle of water, pushed a few crystals of sodium carbonate on one side and on the opposite side they pushed in a few crystals of copper (II) sulfate. After waiting five minutes, a solid dull blue precipitate formed in the middle. Also, the drop tested positive for conductivity.
I used to be big into concept maps as an additional way for my students to show understanding besides a quiz or test. In fact, so much so, that my students a few years ago had to make a concept map as a mandatory test review. I’ve shied away from that over the past few years in a new school (why? I’m actually not so sure) - probably because I got too much information from my students about their level of understanding. I’m sure if I conducted a rigorous method of assessment, there would be a correlation between how well students could connect ideas and assessment scores.
Are kids learning? Given the time it takes to implement and grade the activity, do I get a lot of "educational moments" out of it? Does it fit into the culture of the classroom? Is there a great deal of "conceptually rich" material in the activity that students can build on? I believe that two activities I tried this week fit the bill.
You can perform an orange to black chemistry demonstration using materials commonly found in stores. The reaction appears to be similar to the Old Nassau reaction, but uses greener reagents. This is a great demonstration to do around Halloween time.
There is a hydrate lab which is done by many teachers. Typically, students first use a known hydrate and are provided the formula. As an example, they might use CuSO4 . 5H2O. On paper, they would work through the percent by mass of water in copper (II) sulfate pentahydrate. They then would be given a mass of the copper (II) sulfate pentahydrate, calculate how much water they should lose and then they would heat it and compare the data with the calculated value. Next, they are given an unknown hydrate. They are also given the molar mass of the unknown salt of the hydrate and they have to calculate the molar ratio of salt to water based on their data. Here is one possible way to “tweak” this lab.
We, as teachers, can see that life is sometimes like this and we care enough about our students that we want to try to prepare them for careers and problems that we can’t even imagine….because we believe that good education can empower people to go further and reach higher than they could ever dream….and maybe the journey we will start together begins with a simple question in which the answer may not seem immediately obvious...and that is O.K….
