Planting is an important and reoccurring science unit in the younger grades. I prefer to take an inquiry approach to planting. I’ve already outlined my planting unit, but I want to go into more detail about the key experiment in this unit, available in my Teachers Pay Teachers store. When I ask my students what plants need to grow, all my students answer confidently, “water, air, sun, and soil!”. But the question is – do they really?
Introduction to the Plant Unit
Most of my students have learned about plants, but it is always interesting to put out a variety of seeds and ask what they notice and what they wonder. Few students know that they are seeds and most students are very interested to learn that they are seeds and to observe them closely. This is a nice way to start the plant unit. It’s different than what they are used to and it sparks interest and curiosity in them.
One thing that I want my students to understand is that they can learn information from books and research. We look up these seeds in books to confirm that they are in fact seeds. I also want my students to understand that they have to back up their beliefs with fact, and this is what sparks our main experiment. I ask students what seeds need to grow. Almost all of my students say with confidence that seeds need water, soil, and sun (some can add air). I then ask them, “how do you know?” and they mostly reply with “I just know it”. This sparks the experiment and reinforces that scientists need evidence to prove what they are saying.
Setting Up The Plant Inquiry
This is experiment is an easy one to set up. You take a plastic bag with seeds and all of the elements that the students are saying seeds need to grow. For example, water, soil, and air, and put it somewhere in the sun. Then you repeat these bags but each time taking away one item. For example, a bag with no water or a bag with no soil, or a bag in as much darkness as you can find. Label the bags carefully with the materials inside. It is almost impossible to do a bag with no air, so I tend to explain that to the students and skip it. For the bag with no soil, include soaking wet paper towels or cotton balls to absorb the water and not oversoak the seeds. I also like to put several different kinds of seeds in each bag, but you might choose to just do one type of seed.
Observing the Plant Inquiry
Once the bags are put in place, just sit back and watch them grow. Just kidding- it will take some time! Have the students routinely check the bags for some signs of growth. The first sign will be a sprout shooting up and then roots shooting down. Your students should routinely draw observations of the seeds and their growth. The students will be very shocked to learn that the seed can grow with no soil and no sunlight!
The Teacher Can Learn Too
My students were not only shocked to see that the seeds can grow with no sunlight and soil, but I was surprised too! At first, I thought maybe I did the experiment wrong and exposed the seed to sunlight. And then I remembered… seeds grow underground where there is no sunlight! Seeds don’t need the sunlight – plants do because they make food out of it. So why didn’t the seeds need the food? Well, I looked it up and learned that the seeds are made up of a protective coat and food for the sprout. The seed has all the food it needs to grow until the sprout can make it out of the ground and participate in photosynthesis.
I love teaching my students about plants in a way they won’t expect by starting with an inquiry approach. Students learn that they need to prove what they believe with evidence. They observe the seeds as they grow and understand that seeds can grow without soil, or sunlight, but they definitely need water.
Have you tried this experiment with you students? How did it go?