The scientific method is a way of gaining knowledge by testing things and taking observations. It involves asking questions, making predictions (a hypothesis), testing, recording observations, analyzing results, then drawing conclusions.
In this activity, we’ll use the scientific method to determine which type of soil can sustain a plant’s life the best. Let’s get growing!
- Seeds of your choice
- Paper towel
- Plastic wrap
- Plastic cups
- Various soils of your choice – we recommend using the following soils but it’s up to you:
- Soil from your yard
- Potting soil
- Small rocks or pebbles
- Writing utensil
Part A: Seed Germination
Germination describes the growth of a plant contained inside of a seed into a seedling. So, let’s get growing!
- Fold a piece of paper towel in half, soak it with water, then lay it out flat on the bottom of your bowl.
- Spread a few of your seeds of choice over the damp paper towel, gently pushing each into the towel. Be sure to space out your seeds so that none are touching.
- Stretch out a piece of plastic wrap over the top of your bowl.
- STEM Q for You: What do you think a seed needs to germinate? Water, the right temperature, the right amount of sunlight, and oxygen! Place your bowl with seeds out of direct sunlight: the plastic wrap on top of the bowl traps heat inside. Putting the bowl in direct sunlight would cause the seeds to overheat and they would likely not germinate.
- Take observations each day. What do you notice changing each day? What do they look like? Create a chart and record your observations on a piece of paper.
- This germination method should have your seeds sprouting into seedlings in no time! Depending on the type of seed you choose to use, they should be ready in 2-5 days. Once you can notice roots and the first leaves, you’re ready to move onto part B!
Part B: Planting
- With the help of an adult, poke a hole into the bottom of each plastic cup. The draining hole allows for any excess water to drain out of the soil. Giving your plants too much water can hurt your plant’s health.
- Prepare each of your types of soil by placing a different type of soil in each plastic cup. Try to have the same amount of soil in each.
- Use a toothpick to create a small hole in the soil of each cup.
- Carefully lift one seedling from your bowl by the leaf. Plant its roots in the hole you created in the previous step. Use the toothpick or your fingers to gently fill in the hole with soil.
- Repeat steps 3-4 for each of the other types of soils.
- Place all of your potted plants onto a tray so that any water that drains out the bottom does not make a mess. Choose a location for your plants to grow. Consider placing them somewhere where all the conditions plants need for growth will be met.
- Make a prediction! Which of the soil types do you think your plant will grow the best in? Which of the soil types do you think the plant will not grow very well in?
- Create an observation chart to record the growth of your plants in each soil type each day. Be sure to water them every day! Take observations over at least a week to collect noticeable changes.
The STEM Behind the Fun
Were your predictions correct?
Which of the soil types did the plants grow the best in? Soil that is able to drain water and hold nutrients well will be the best choice for growing plants.
Which one of the soils meets these requirements? This should be the soil that your plants preferred the most.
What are the main types of soils? What is the difference between them? Sand particles are very large so it dries very quickly and does not hold nutrients well. Clay has very fine particles which helps it to hold nutrients that plants need, however, this also causes the soil to drain water very slowly. Silt has medium sized particles and has better drainage ability than sandy soil but a lower ability to hold nutrients than clay. Loam is a mixture of all three soil types (sand, silt, and clay).