Today I would like to introduce a very important point in practical part of biology olympiad. In various experiments you need to make dilutions in order to get results. So if you want to understand and learn how to make either simple or serial dilutions, read carefully the documents below. Good luck!
A good tutorial about dilutions can be found HERE.
Another good link is: bbruner.org/dl/dil.pdf.
One more: https://matconline.matc.net/ICS/icsfs/Dilutions_and_Micropipetting.docx?target=51197ebf-36a1-4c95-a050-24ab8035c727
Serial dilutions are described at: http://mathbench.umd.edu/modules/measurement_serial-dilution/page04.htm
Image source: https://www.freepik.com/vectors/lab-room