Take an iron stand with the clamp. Take a cotton thread of about 60 cm length. Tie it to the clamp so that it hangs freely from it as at the free end, suspend a pen so that weight can be placed in it. Add weight one by one till the thread breaks. Note down the total weight required to break the thread. This weight indicates the strength of the thread. Repeat the same activity with threads of wool and steel of similar length and thickness. You will observe that nylon thread is strongest among them.