Looking at your experimental data for Beaker/Tube B. The percent concentration of both fluids is different. There is % sugar in the beaker and % sugar in the dialysis tube. Now, think of it from the water's point of view. There is % water in the beaker and % in the dialysis tube. So the beaker has a concentration of water than the dialysis tube. When you put the dialysis tube in the beaker, the water will flow across the tube's membrane and the tube.