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    Seed Structures
    Overall Objective
 

To learn about seed structures. To observe seed germination and to compare seedling development for different kinds of plants.

 
    Lessons
 
 
    Seed bags
    Objective
 
To let students observe changes as different types of seeds germinate.
   Overview of Lesson
 

Students observed four different types of seeds throughout the germination process. Students "planted" one bean, corn pea, and squash seed in vermiculite in a Ziploc bag. (Paper towels could also be used to keep seeds moist.) A single, dried seed was mounted on the outside of each bag so that students could compare the appearance of a dried seed to the soaked and germinated seeds. The bags of seeds were watered and taped in a sunny window. Each day for 9 days, students carefully removed the seeds from the bag and made observations . They recorded their observations in their seed journals. Students were asked to note changes in size, color, and shape.

   Children's Thinking Druing Lesson
 

Students observed the bags daily and recorded their observations on their record sheets. Students were instructed to draw their seeds each day and write down as many details as they could observe.

On day 1, many students recorded size or color changes like, "skinnier and greener and brown," "softer, smaller, a little white, light yellow," or "haven't got much bigger than yesterday when I planted it. The color is the same."

As the unit continued, some students became more detailed in their descriptions and pictures. For example:

"My pea seed[ling] is 5 1/2 cm long. It has 2 roots that are brown but at the end of one it looks like a leaf is growing. The seed is brown and white."

"One of my roots is 4 inches long. The stem is 2 inches long and the leaf is green."

"It got bigger and darker. I can see the seed coat coming off and the little leaf got longer and the root got longer and it curved. I can see the seed is going to split in half."

Many children know the conditions seeds need to grow but were unaware of seed parts and details of seedling growth. The terms embryo, roots and root hairs were unfamiliar. After ten days of observing seed bags, students demonstrated better understanding of the structure of seeds and could name and label the parts. Questions were posed, "I wonder why my squash grew the most but some other people's seed didn't grow at all?" Students paid more attention to details like the seed coat coming off and roots and root hairs emerging and elongating.

Some seeds didn't develop as quickly as others. This caused concern for some children. Students struggled with the vermiculite, seeds not being carefully handled and parts breaking off or too much moisture causing decay.

Students' observations changed from describing size and color to labeling parts, using accurate measurement, and showing their understanding of functions of seed features. Children came to see the seed as food, and notice the development of roots, root hairs and shoots.

Students found that collecting detailed data was important if they were to address questions that arose later in the unit. Studying seed bags answers some growth questions and prompted students to pose new questions. Also, it helps students see the process of germination: seeds turning into seedlings then into plants that produce more seeds to complete their life cycle.

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Last Updated: February 17, 2005
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