What makes a root?
Lesson 6 of 12
Objective: SWBAT describe how roots help a plant to survive, grow, and meet its needs.
In this lesson, students are working towards NGSS standard 1-LS1-1. Use materials to design a solution to a human problem by mimicking how plants and/or animals use their external parts to help them survive, grow, and meet their needs. The first step in unpacking this standard is for children to understand the structure and function of external plant parts. Today we explore roots and how roots help plants survive.
Part of the NGSS Science & Engineering Practices call for students to actually make observations. I teach this lesson a few days after the class plants seeds, when roots and shoots have started to grow. (For example, if you plant on a Friday, by the following Monday or Tuesday, you'll be ready for this lesson!) Students can also observe photographs or videos of roots, in order to provide them with a wealth of background knowledge about types of roots.
As a warm-up, we'll activate our schema by discussing what roots we eat and what we know about roots. Then, we'll watch a time-lapse video of a plant growing as we connect to our prior knowledge of the plant life cycle. Next, we'll observe our actual plants. We will draw and label the parts we see thus far, including the roots.
We'll also read an online text to answer the question, "How do roots help plants survive?" and write to tell why roots are essential parts of plants. In closing, we'll observe the changes of celery placed in water with food dye overnight.
In the previous lesson, we discussed many vegetables, including root vegetables. Root vegetables include carrots, beets, radishes, parsnips, sweet potatoes/yams, and onions (plus a whole lot more I have never tried personally!).
As a warm-up, we'll activate our schema by discussing what roots we eat and what we know about roots. I ask, "Have you ever seen roots on a tree?" By connecting to personal experiences, such as tripping over roots or seeing them break up a sidewalk, students then create a mental image of roots to aid in their understanding.
Finally, I ask, "How do roots help plants survive?" It's great to see what students know about this question, as it gets to the NGSS standard of the function of external parts. It is possible that some of your students will know one of the 3 main functions of roots: to anchor the plant into the soil, to transport nutrients into the plants stem, and to absorb water.
When my class completed a Schema anchor chart about plants at the beginning of this unit, many knew that roots bring water into the plant. My students have marbled composition notebooks as dedicated Science Journals. To begin today, they write the question, "How do roots help plants survive and grow?" We record reason #1, which was prior knowledge. And now we have a purpose for the lesson-- to find 2 more purposes of roots!
Since our class plants (all types of beans) still have quite small roots, I begin by showing a time-lapse video of roots growing. I set the purpose for watching the video by saying:
Friends, today we will watch a time-lapse video. Time-lapse videos are special because they speed up what actually happens in nature. For example, the video we are about to see takes 20 days and turns it into just one minute! It lets you see changes over time more quickly.
As we watch the video, infer what you think the purpose of roots are. To infer means to make a smart guess, and scientists make smart guesses all the time. Then, we'll read and check on our celery experiment to see if we were correct.
After watching, students turn-and-talk to discuss how they think roots help a plant survive. In this video, there are plenty of water droplets and the roots reach way down into the pot to reach the water. I expect students to answer that roots bring water up into the plant.
Then, I come back to the standard and ask, "How does bringing water into the plant help the plant to survive and grow?" Now I expect them to answer that all plants need water to survive and will not grow without water (which they stated when we discussed plant schema in Lesson 1).
Next, we read an online article about the function of plant parts. There are two really good ones, a National Geographic Young Explorer Magazine, p.10, "Seeds Grow" and a BBC article on plant parts. I choose to read the National Geographic article because my school orders paper copies and I like to have students read along in paper copies. There are also digital versions online for free, if your students have one-to-one devices. I add the link to the second video in my computer center for students to complete additional research during reading and writing time.
Before reading, I set the purpose, "Today as we read, we will define the function or purpose of roots." While reading, we also pause on each page to discuss how the seed, sprout, and adult plants all look different. I facilitate the conversation by asking, "How do the phases of the plant look alike and different from one another? This discussion moves students towards NGSS standard 1-LS3-1. Make observations to construct an evidence-based account that young plants and animals are like, but not exactly like, their parents.
After reading, I play a transition song. Before I play the song, I tell students that today they will be observing our plants and recording their observations in their Science Journal. I have dedicated marbled composition notebooks for each child, however, there are adorable plant journals online too that you can print. My students glue in a recording page and begin drawing and labeling the parts of the plant they can see. Below, they write to tell the purpose of roots.
I play a transition song. Before playing the song, I tell children that by the end of the song, they are to put their plants back in the grow lab, put their notebooks away, and meet me back on the rug.
Once we are back on the rug, I remind children that yesterday we placed celery in colored water. You can also use white carnations. Granted, the celery no longer has roots; however, the stems are cut just above the root. If the roots and stem worked to help the plant survive, what do they predict might have happened? How would the celery changing color show that water goes up through the roots, through the stem, and to all parts of the plant?
I kept the celery in the classroom next door overnight, and I make a big fuss as I bring them over. Magically, the celery stalks have changed color! I tell friends that I think it was magic. Then I ask them, "Was it really magic, or can we explain this through science?"
Here is a before and after journal, where your students can explain what changed and why. My students recorded in their science journals instead.