• If the substances become wet, take a clean spoon and carefully remove the pile of sugar, salt or baking powder and replace it with the same amount of fresh sugar, salt or baking powder. Make a note of how often you changed the pile for each substance. Which of the substances became wet first? How often do you think you will have to replace the salt, sugar or baking powder?
• After 30 minutes remove all the sugar, salt and baking soda from the cucumbers (keeping track of which slice had which substance on in). Use your fingers to clean the cucumber slices of any remaining substance. When touching the different cucumber slices, how do they feel? Do they feel different? Do some still feel crisp or did they become squishy?
• Once all your cucumber slices are clean, if you have a kitchen scale, you can weigh each cucumber slice and note any changes. Compare this value with the number you wrote down in the beginning. What happened to the cucumber slice during the activity? Did it become heavier or lighter? Comparing the different substances, which one resulted in the biggest change? Can you think of a reason why?
• Finally, cut your cucumber slices in half and compare the texture and thickness of each slice with that of your control. Did their texture and appearance change? If yes, how? Did the slice thickness change? Which substance had the most noticeable effect? What does that tell you about the substance's ability to attract water?
• Extra: You have tested salt, sugar and baking soda in this activity.Now, can you think of other substances to try that might be hygroscopic?
• Extra: During your test of some of these substances, the cucumber lost a lot of water. Do you think you could rehydrate the cucumber again?After your dehydration test, try placing each cucumber slice into a clean cup of fresh water and let it sit overnight. Do the cucumber slices look different in the morning?