Observing Bulbs
Part I: All About the Outside

Overview: Your tulip bulbs have arrived and you're about to bury them underground. But before you start digging, maybe you should ask yourselves,

"What ARE these things we're using to gauge the greening of spring?"

Science begins with observation. By looking closely, you just might get some ideas about what will happen in the spring! Start by exploring bulbs from the outside before moving to the mystery inside.

Laying the Groundwork: Selecting Bulbs
Divide the class into groups of 3 to 4 students. Have each student select the bulb he or she will plant this fall (and observe during this lesson).

Exploration: Bulbs, Up Close

  1. Observe and draw. Pass out copies of the My Tulip Bulb journal page. Ask students to use the first box (What I See) to draw a picture of the bulb. Encourage them to look first at the whole bulb and then notice details of different parts (e.g., the shape of the top and bottom, how the skin looks). Once they've looked with their eyes alone, hand out magnifying lenses if you have them. What more do they notice?
  2. Share and describe. As students use their eyes and other senses to explore bulbs, have them discuss their discoveries in their groups. Circulate and, if needed, help students write descriptive words for each of their sensory observations. Encourage them to use words that could paint a picture for someone who had never seen a bulb before. Create a class chart of these words and phrases and a list of "What I Wonder" responses. These can inspire more investigations. (See What If . . .? Time to Experiment!)
  3. Compare. Ask each group to compare its bulbs and notice how they are the same and different. Put out string and rulers, tape measures, scales, or other measurement tools. Challenge groups to line the bulbs up from smallest to largest or lightest to heaviest.

    Next, have each group change places with another group so students can compare even more bulbs. Make a class list of the similarities and differences students noticed.

Option for older students: Print a copy of these graphs for each student. Have them weigh and measure their bulbs as described on the handouts. Next, plot the weights and circumferences of all the bulbs in your class. Have students answer the handout questions in their journals.

Note: When planting this fall, mark the location of each student's precious bulb with a popsicle stick. As extra insurance, label each location on a garden map.

* Tulip Bulbs (1 per student)
* Magnifying lenses (optional)
* Measuring tools (see Step 3)
* Journal page: My Tulip Bulb (pictured below)



Tip: If your observations span several days, store each bulb in a paper cup marked with the student's name. Keep in a dry, cool, dark place.




Graph of Bulb

Graph of Bulb