The First Part
Prepare a concrete block with the ideal water-concrete ratio; which is normally 1:4, or a maximum of 1:2. This means that for 4 or 2 bags of cement, there should be 1 bag of water (hypothetically speaking). In this case, mix one cup of water in 4 cups of cement.
The Second Part
Now prepare another concrete block by keeping the water ratio high. This means that instead of using 1 cup of water in 4 cups of cement you should mix 2 cups of water in 2 cups of cement.
Making concrete blocks
Now both the mixtures should should be poured in cardboard boxes to prepare the concrete blocks. However, it is advised to oil the inner sides of the cardboard boxes to prevent concrete from sticking to it. Mark both the boxes as Block ‘A’ and Block ‘B’ respectively for the each of content mentioned above.
Hardening of concrete
After the concrete is poured in the cardboard boxes, give it time to dry and become hard. The process may take a few hours. It's advised to keep it on warm and dry place, preferably in open air.
Testing concrete blocks strength
Once the concrete in each box has dried, pull the blocks out by tapping a heavy hammer or hydraulic press on the box. It will be noticed that the concrete block with higher water content breaks down easily as compared to the one with higher cement content.