A scale that only goes to 1g is really only accurate to +/-0.49g. That is, when it it says 1g, it could really be anything from 0.51g to 1.49g. Your way is probably better. The larger the quantity you weigh, the smaller the error relative to the quantity measured. Unless you're making a really small batch, it probably is better to put 10g yeast in 990g water for 1% yeast or 0.1g per 10g solution. You would then use 50g of the solution for 0.5g. This would reduce the possible error by one order of magnitude.
Craig.
Would you please take a look at the screen shot below. There is something that troubles me and I didn't want to scare Judy off on this measuring situation of her's if it's just something I can't wrap my head around.
The screenshot won't download!

Please plug .5 into converter you need to select "yeast" from the drop down ingredient list first.
http://www.convert-me.com/en/convert/cooking/Notice in the right metric box I entered .5g for conversion the left US convert box kicks out 0.08247 tsp.
Can that be rounded off and just call it 8 hundredths of a tsp. for convenience sake?
Now, if a "smidgen" spoon is 0.050 tsp. 1 and 1/2 smidgens would get you close, correct?
When you look at the amount of yeast in the ramakin on my scale....how come that amount looks waaay more than 8 thousandths of a teaspoon?
8 thousandths sounds like it should only be a few grains sitting inside of a big ol teaspoon. no?
Am I doing something wrong here Craig; thanks for the help!
Bob