There is also an Osmosis Detectives group packet handout for sale in my store that goes with this PPT and activity.
This is an osmosis simulation activity I do because we don't have class periods long enough to pull off an actual diffusion lab with dialysis tubing.
The morning before this activity, I take 5 balloons (per group of kids) and fill them up with water to various amounts. One tiny, one a little bigger, a medium size, a little bigger, and a biggest. I always take the mass of the medium sized balloon and secretly make that my "isotonic cell".
I let that particular group know that all of their cells started at that mass. From their they will mass all the cells and figure out if it was in a hyper, hypo, or isotonic solution, and then figure out which solution each cell was in.
I take 5 large beakers fill them with water and use food coloring to make each of the five solutions a different color.
I think make a different sugar concentration percentage for each solution. Make sure that one of the (the one that will end up being the isotonic solution 25% (because that's what the student's worksheet tells them is the concentration inside all of their 'cells'.
For this activity you need five large beakers, balloons (5 per group), sink to fill balloons, scales, and I also have the students weigh a paper bowl and put the balloons in the bowl when they mass them (then subtracting the mass of the bowl). This just helps the balloons to not slide off of the scale. They will also need calculators.