Precision is everything in science. When it comes to quantitative data in any science discipline, there is a limit to how precise a measurement can be. For example, a ruler that does not have mm markings is not capable of measuring the length of an object beyond 0.1cm. However, a ruler that does have mm markings is capable of measuring to the nearest 0.01cm. While this seems like a minor difference, it changes the degree of precision when it comes to data collection dramatically. Unfortunately, when it comes to lab equipment, precision comes with a cost.
At NTHS, one of the analytical tools we use most often when it comes to data collection is an electronic balance. We currently have about 8 electronic balances, capable of measuring the mass of an object to the nearest 0.01g. These balances are typically about $250-300 each. By comparison, a balance that measures to the nearest 0.1g costs about $125.
However, due to the nature of some of our experiments, that kind of precision is just not enough and results in students not getting the most precise result that they could get. Data analysis is a core academic skill in math and science, especially with the integration of the Next Generation Science Standards. Therefore it is crucial that the data students obtain good and reliable data to ensure proper analysis for their understanding and engaging in evidence-based argumentation.
It is our hope to be able to secure funding through an Excellence in Education Grant to fund the purchase of an analytical balance. This balance will be capable of measuring mass to the nearest 0.0001g and has a load capacity of 220g. This will allow our students to make mass measurements of the smallest of samples, enabling them to do highly precise analytical processing of their data. These balances, due to their high degree of precision, are quite expensive. The funds from this grant would be used to purchase a FLINN analytical balance, one of the best economical choices, for about $1575 (most analytical balances with this amount of precision usually cost more than $2000).
Having the opportunity to have an Analytical Balance in the classroom really does open the doors for our students when it comes to data collection. In chemistry specifically, one of the core analytical units we cover is Stoichiometry. Stoichiometry is essentially the study of mass and volume relationships in a chemical reaction. It allows us to determine formulas of chemical compounds, predict how much of a specific mass or volume to expect from a given chemical reaction, and also how to analyze the efficiency of a chemical reaction. An analytical balance allows students to make the smallest of mass measurements, ensuring a high degree of accuracy of their results, especially with units like this. Some of the experiments this balance will help our students the most are:
1. Empirical Formula of Magnesium Oxide
2. Mole Ratio of Silver and Copper
3. Empirical Formula of Silver Oxide (AP Chemistry)
4. Gravimetric Analysis of a Metal Carbonate
The purchase of this balance through Flinn, one of the largest science equipment suppliers for education in the country, offers several benefits. For the balance itself, it has a fairly high load capacity, compared to most balances. Load Capacity is the maximum amount of mass the balance can measure. It is also the largest source of equipment failure, where students load too much mass and overload the balance. Another great feature of the balance is that is comes with calibration weights, so that accurate measurements can be sustained over time.
Allowing our students to have access to the same analytical tools that scientists equips them to make real meaning of their data, which supports the instructional shifts of an NGSS classroom. At a time when student exploration and experimentation is the driving force in the acquisition of content in the classroom, students must have access to modern technology and analytical equipment that supports their work.
With the implementation of NGSS into our science classes across the state, there is more of an emphasis than ever before on science and engineering practices. This translates into more student exploration activities, that value the content just as much as the process by which they obtain that knowledge. Research has shown that students who engage in data-driven lab activities deepen their understanding of content. Our chemistry classes at North Tahoe High School are very "lab-driven." We want students doing science and being scientists regularly, equipping them with the best analytical tools that we can to provide a learning environment that promotes high-level data analysis. In this sense, we really use the results of our lab work to drive learning outcomes. While the balances we currently have would suffice for some lab activities, they are just not able to obtain the level of precision we need for an accurate result. Prior to my time here at NTHS, I have always had my students have access to an analytical balance and it has always resulted in our class being able to do highly analytical activities that we would not have otherwise been able to do with a standard classroom balance.
When I define success of this program, I think of the many students that will be able to use this tool regularly, engaging them with highly precise and accurate results, and using them to understand core foundations of chemistry. And in our classroom as a whole, tools like an analytical balance really do support the lab-driven approach that our class takes, ensuring students are capable of achieving lab results that really make sense of the work we are doing.
Itemized purchase and shipping quote is attached above. There are many different analytical balances are the market. Most of them are developed for commercial laboratory use and not in the classroom. This recent balance by Flinn is by far the most economical choice and is designed to stand up to student use over time.
The implementation goal, due the new Spring cycle of the Excellence in Education Grant, is to have an analytical balance purchased early in the Fall of 2018. This would allow students to enjoy the use of this piece of equipment from essentially the start of the school year. This will be extremely beneficial early in the school year for our AP Chemistry students, who essentially start the year by doing gravimetric analysis studies of chemical reactions. Several of those experiments, which are designated by College Board, require students record mass measurements only achievable through the use of an analytical balance. College prep students in chemistry will use them early in the year as the study bulk properties of matter, and again in the middle of the year when we also do gravimetric analysis studies.
Students in these courses all work in lab groups, where there are designated roles for each of the students in the group. One of those jobs is data manager, who is responsible for actually collecting the quantitative data and communicating it with their groups. Students will take turns using the balance, as well as proper lab technique when it comes to measuring the mass of chemical reagents.
The hope is that this balance will have a long life at its new home at NTHS, and we would not require any additional funding beyond this initial purchase to enjoy its use in our study of science.
The beauty about having an analytical balance is that its use is not limited to chemistry, though its use is primarily aligned with chemistry lab activities. In fact, any science discipline that uses mass measurements can benefit greatly from its use. This would include Biology, Physics, AP Biology, AP Chemistry, AP Environmental Science and AP Physics. All of these disciplines incorporate lab activities that have students taking mass measurements, where the precision and accuracy of the measurements they take have major impacts on their analysis and meeting lab objectives. Currently at NTHS, there is a growing enthusiasm for science, where we have more students signing up for AP sciences than ever before. It is important that we support the learning of our students in these courses by providing them authentic learning experiences in the lab by having the proper equipment.
The primary funding sources that would be available for this program would be Measure A funds. There are two designations for those funds: a small amount for classroom use and Measure A science funds. However, those funds are used regularly to maintain chemical inventories, biological consumables, and maintenance of laboratory equipment. For example, this balance purchase alone would have depleted the entire science allocation for Chemistry for the 2017-2018 school year. Due to the magnitude of this particular request, site funds would not be sufficient to cover these expenses and maintain what is currently used for science consumables and equipment.