I agree with Dr Hussain. DMSO is not suitable for extraction due to toxic nature. You should try 70% methanolic water solution or 100% methanol for extraction. the ratio of the solvent should keep in to 1:10 (W/V) material/solvent.
I also agree with Dr. Hussain, and point out that this is a High School. If methanol is available then great, otherwise use ethanol. Isopropyl could also be used. It only really matters if extraction efficiency is part of the study.