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How do tomato seeds germinate?

Above: Image © Allexxandar, iStockphoto.com

Overview

Students will make a CD Case Germination Viewer to germinate tomato seeds and make daily observations to practice their skills of observation and recording to explore the process of germination.

Inquiry Skill Development

  • Observing changes in seeds and seedling structures as seeds germinate
  • Recording observations based on comparing and contrasting

Concept Development

  • To introduce and explore the concept of germination
  • To identify and introduce the names of a seedling’s parts as it germinates

Prior Knowledge and Skills

  • Basic plant anatomy
  • Basic understanding of the role of seeds

Success Criteria

  • Students observe seeds germinate
  • Students record in sequence changes to the seed that take place using drawings or photos
  • Students identify and name the parts of the seedling that develop during the germination process

Suggested Timing

  • 30 - 40 minutes in class to set up CD Case Germination Viewers
  • 10 - 15 minutes daily for 7-10 days for observing and recording

Materials

Note: Darker colours of felt, such as brown or green, are preferable for observing the emerging roots and shoots.

  • CD cases – transparent, thick-style case (1 cm depth)  - 1 per small group of 3-4 students

  • Felt – 1 square per CD case, cut to the size of the CD case

  • Tomato seeds – 3-4 seeds per case; use seeds collected from tomatoes at home or purchased from a gardening center; the type or variety of tomato does not matter

  • Access to fresh water

  • Magnifying glasses or stand magnifiers

  • Optional: Plastic pipettes or medicine droppers for watering

  • Sequence Organizer Linear Template – 1 per student doc pdf

  • How does a seed grow? - Kids Want to Know (Video on Tomatosphere™)

  • BLM1: Vocabulary Preview – How does a seed grow? (video) – 1 per student doc pdf

  • Seeds and Germination – (Tomatosphere™ Backgrounder)

  • Optional: Tomato Seed Germination Timelapse with Macro Lens - Maxime Ayotte (Video on Tomatosphere™)

Tips for Success

  • Organizing working groups prior to the lesson is highly recommended to save time.
  • If possible, ensure each student has a seed to observe in the group cases.

Minds-On

Introducing the inquiry

Step 1

To introduce the topic of germination, ask students the following questions:

  1. What happens when a seed is planted?
  2. How do you know that a seed has sprouted? What evidence is there?
  3. What parts of a seedling can be seen once a seed has sprouted?

Step 2

Optional: View the video Tomato Seed Germination Timelapse with Macro Lens

Follow-up the video by asking students:

  1. What part of the plant cannot be seen in the video?
  2. What do you think is happening under the surface of the soil?
  3. How could we find out what is happening below the surface?

Step 3

Tell the students that they are going to put tomato seeds into empty CD cases so that they can watch the seeds sprout (or germinate).

Preparing the CD Case Germination Viewers

Step 1

Pre-soak the tomato seeds for about 20-30 minutes to help soften the seed coat and initiate the germination process.

Step 2

Distribute the CD cases and felt to each student group. Instruct students to cut the felt into a square that fits inside the CD case. Alternately, the felt squares can be cut ahead of time. Have the students wet the felt so that it is quite moist and place it into the CD case.

Step 3

Distribute the tomato seeds to the students and instruct them to place the seeds in an evenly spaced line across the middle of the felt. Students should put a maximum of four seeds into each CD case.

Step 4

Place the seeds in a warm location in the classroom where they will get some light during the daytime. Make sure that the seeds do not get too hot or that the felt dries out. In cold climates, the seeds may get too cold or freeze on a windowsill, so another warm, bright location in the classroom may need to be found.

Step 5

Water the seeds each day. A plastic pipette or medicine dropper inserted around the edges of the case will help with this task. Try not to open the case to add water and only add small amounts of water at a time to prevent the seeds from being washed out of the CD case or damaged.

Action

Doing the inquiry: Observing and recording the germination process

NOS Alert: Remind your students that they are doing science by making observations of plants, which are an important part of the natural world (or nature).

Step 1

Ensure students have 10-15 minutes each day to make observations of their seeds in the CD case viewers. If available, provide magnifying glasses and/or stand magnifiers to help students make observations.

Step 2

Provide each student with a copy of the Sequence Organizer Linear Template. Have students start the organizer on Day 1, the day the seeds are placed into the viewer. Instruct students to draw a picture of the seed(s) in the viewer and describe the appearance of the seed(s) in the space provided.

Step 3

Each time there is an observable difference in the appearance of the seed or emerging plant, have students draw their observations and describe the changes taking place on the sequence organizer.

Step 4

Continue to make daily observations until the seeds have small leaves (cotyledons). See Figure 2.

Step 5

Introduce the students to the names of the parts that are emerging from the seeds as germination takes place. With primary students, these terms can be simple, such as the shoot, root, stem and leaves. Beyond the primary grades, and based on curricular requirements, the botanical terms describing the parts of germinating seeds may be introduced and defined. To learn more about the germination process and these terms, see the Seeds and Germination educator backgrounder.

Step 6

The observation period for this inquiry will end shortly after the seeds have developed cotyledons.

Step 7

You can try to keep the seedlings growing by gently opening the case a little. It is challenging to transplant seedlings started in this way because the roots become stuck to the felt. If you do attempt to transplant the seedlings, lift the felt out and cover the roots portion with soil, leaving them attached to the felt. Ensure the stem and leaves remain above the soil and keep the soil moist.

Consolidation

Reinforcing the concept of germination and new vocabulary

Step 1

Follow-up the inquiry by watching How does a seed grow? (Video on Tomatosphere™)

Step 2

Prior to showing the video, have the students participate in a Vocabulary Preview learning strategy. Provide each student with BLM1: Vocabulary Preview – How does a seeds grow?, for the video. Instruct students to read the words listed and categorize them into the different columns on the page. For the words that students know, instruct students to use them in a sentence in the right column.

Step 3

After viewing the video, discuss the words that were new or still confusing to students. Provide additional explanations for these words as necessary.

Extensions

  • Germinate other types of seeds in the CD Case Viewers.
  • Display the completed sequence organizers in the classroom, on the class website, etc.

Additional Information

Let's Talk Science Resources:

The Tomatosphere™ team is interested in collecting exemplars and photos of our learning strategies in action. Please consider sharing with us at: tomatosphere@letstalkscience.ca