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Hi colleagues, I am struggling with conservation of mass labs in 5th grade due to lack of accuracy on their part in measuring. I have tried a chemical reaction before and after, with a balloon over the flask, and also ice melting in a baggie before and after. In both cases, the students are not able to accurately measure on the triple beam balance, so they get different before and afters.  Has anyone else had this problem? Would digital balances be more accurate? My students have a lot of practice with the balances and the seem to do great with relative mass, i.e. figuring out which is heavier, but when it comes to accuracy, they are definitely off.

Hello, I have minimized the usage of the triple beam balance. Instead I use the digital scales. They work real well.

Digital scales are definitely something to think of using. This way there is less room for human error.

A human can make an error reading a digital balance just as easily as a triple beam balance. You should try it yourself a few times just to see what the approximate range should be for the measurements. You are expecting all of the numbers to add up? Maybe there are other losses of mass that aren't considered. Are the masses too small to be measuring on a triple beam balance? Electronic balances are nice, but they will need to be careful about them for the following reasons. [ol]