Using only these supplies, which question can Mabel investigate with an experiment?
If squash seeds and tomato seeds are planted with compost, which type of plant grows larger? Do squash plants grow larger if the seeds are planted in small pots or in large pots? Do squash plants grow larger if the seeds are planted with compost or without compost?
Mabel has a small vegetable garden, which includes a compost pile of food scraps. She notices that some of the squash plants growing next to the compost pile grow differently than squash plants that are farther away. She wonders what factors affect how her squash plants grow. So, she decides to design an experiment. She has the following supplies available:
one type of squash seeds
four large clay pots
soil
a compost pile
water
Experiments can be designed to answer specific questions. When designing an experiment, you must identify the supplies that are necessary to answer your question. In order to do this, you need to figure out what will be tested and what will be measured during the experiment.
Imagine that you are wondering if plants grow to different heights when planted in different types of soil. How might you decide what supplies are necessary to conduct this experiment?
First, you need to identify the part of the experiment that will be tested, which is the independent variable. This is usually the part of the experiment that is different or changed. In this case, you would like to know how plants grow in different types of soil. So, you must have different types of soil available.
Next, you need to identify the part of the experiment that will be measured or observed, which is the dependent variable. In this experiment, you would like to know if some plants grow taller than others. So, you must be able to compare the plants' heights. To do this, you can observe which plants are taller by looking at them, or you can measure their exact heights with a meterstick.
So, if you have different types of soil and can observe or measure the heights of your plants, then you have the supplies you need to investigate your question with an experiment!