Making a prediction!
Before testing, get into groups of three students and discuss your scientific predictions.
I predict that the cucumber seeds will…. (circle the answer)
Float – Sink
Make a sound when dropped – Not make a sound when dropped
Have a visible embryo – Not have a visible embryo
Germinate – Not germinate
Now, you are ready to starting your experiments! Check the list below when you’ve completed each experiment.
1. Do the cucumber seeds float? Remember, filled seeds will sink while empty seed will float. Write your observation here.
2. Do your dry cucumber seeds make a sound when you drop them on a hard surface? Remember, scientists listen for the sound the seeds make when dropped onto a hard surface – empty seeds and filled seeds sound different. Describe the sound here.
3. Use sharp scissors to cut one of cucumber seeds in half then look at it very closely using a hand lens or microscope to look for the endosperm and embryo. This is what scientists call a ‘cut test’. Write your observation here.
4. Draw what you see inside the cucumber seed.
Now that you’ve tested your cucumber seeds for ‘fill’, it’s time to test for viability and germination. Remember, viability testing is learning whether a seed is alive or not. But germination testing is asking whether the seed is ripe enough.
5. Take some cucumber seeds from the packet and divide them into three groups for testing under the same conditions but with one variable. The variable you are going to change is ‘storing’ them three different ways before germination.
|At the Australian PlantBank, scientists use cryostorage to keep seeds for the future. Cryostorage means freezing the seeds at a very low temperature.
||Some seeds don’t need to be stored in any special way, just kept dry and safe. But not too dry! When seeds are too dry, this is called ‘desiccation’
||Some seeds don't mind getting their feet wet and in fact germinate faster if they’ve been kept wet.
- Place these cucumber seeds in the school freezer overnight.
- Place these cucumber seeds somewhere dry and safe overnight.
- Place these cucumber seeds in a glass jar of water overnight. You don’t need to put a lid on top.
6. Now, it’s time for the final stage of your experiment – planting the cucumber seeds! Take all of the three test groups and get ready to plant them. If all three sprout into plants, then you know that cucumber seeds can be stored frozen, dry or wet and still remain viable. If some don’t sprout at all, then you know that some conditions just don’t suit cucumbers.
Do you think all of the seeds will sprout? And will they sprout at the same time? Will some take longer than others? If yes, which ones?
To make sure you know which group is which, prepare some labelled seedling trays. You’ll need three trays – one for each type of storage. Remember, it’s important to keep everything in your experiment fair and accurate, so use the same soil for each tray, the same amount of water and put them in the same (sunny) position. Follow the instructions on the seed packet for more information.
Over the next few days and weeks, write your observations in your workbooks. You could write them as a “Diary of a Cucumber”.