is approximately the density of water under room temperature. The wood block will sink to the bottom of the cylinder if its density is greater than that of the water.
Steps for measuring volume of the wood block assumes that the wood block would float on top of the water. Otherwise there shall be no need for pushing the block underneath the water surface as in step b. The observation is now in conflict with the assumption. It is necessary to repeat the experiment. Consider revising the assumption and procedure if the discrepancy persists.