Beacon Lesson Plan Library

Centimeter Slinkies

Laurie Ayers
Bay District Schools


This activity is a fun way to investigate measuring in centimeters. The student estimates & measures the length of a whole color-segmented, candy gummy worm. Then, as students bite off each segment, they estimate, measure and record findings in an activity log.


The student uses a wide variety of concrete objects to investigate measurement of length, weight, capacity, area, perimeter, and volume (for example, cubes, grid paper, string, squares).

The student using real-world settings, objects, graph paper, or charts, solves problems involving estimated measurements including the following: length to nearest inch, centimeter; weight to nearest pound, kilogram; time to nearest half-hour interval; temperature to nearest five-degree interval; and money to the nearest $1 or $10 (combination of coin and currency).


-Color-segmented gummy worms (enough for each student with a few spares)
-Recording sheet for each student - Centimeter Slinkies Activity Log (see associated file)
-Centimeter rulers (one per student)
-Meter stick which also shows decimeters
-Overhead and several small objects that could be measured in length in centimeters
-Clean paper to place the gummy worms on when measuring
-Math journals or a piece of notebook paper for each student
-Copy of the rubric (see associated file)


1. Gather materials for activity.
2. Make copies of the chart worksheet for students to record estimates and measurements of their worms.
3. Make a copy of the rubric for the teacher's use.


NOTE: This lesson addresses estimating and measuring length to the nearest centimeter only.

1. Ask students if they have ever eaten a worm.

2. Open a bag of gummy worms and dramatically put one in your mouth!

3. Encourage students to share about their experiences measuring length and explain that today the class will use gummy worms to learn about measuring with centimeters.

4. Discuss centimeters, making comparisons with decimeters, meters, inch. Also discuss the abbreviation for centimeter (cm) and write the word centimeter and the abbreviation on the board or overhead. Model estimating and measuring several small objects using a centimeter ruler on the overhead, making sure the students understand how to align the left end of the ruler with the beginning of the object being measured on the left. Call upon several students to also model this behavior.

5. Distribute activity materials (worms, Centimeter Slinkies Activity Log provided in associated file, rulers). Tell students they will be assessed on completing the activity, recording their data correctly, and estimating and measuring as carefully as they can. (See criteria listed in the Centimeter Slinky Rubric located in the associated file.)

6. Ask students if they think all the different colored segments of the gummy worms are the same lengths. Briefly discuss their observations.

7. Encourage them to estimate the total length of their gummy worm to the nearest centimeter, and write the estimate on the activity log worksheet. Have students measure the actual length of the worm to the nearest centimeter. (At this time introduce the assessment criteria for the chart. Discuss)

8. Ask students to estimate (guess) how long their worms will be if they bite off one of the colored segments.

9. Instruct students to bite off the first color segment of the gummy worm. Yum! Now that they have taken the first bite, have them look at the worm again and estimate the length. Record the estimated length on the activity log.

10. Have students measure the actual length of their worms and record that measurement on the activity log. Have students compare their estimates to the actual length. Were they close? Can they do better on their next section?

11. Repeat the procedure until the entire gummy worm has been consumed.

12. Encourage students to compare the data on their activity logs. Did their estimation skills improve with each bite? Allow ample time for discussion and feedback.

Special note:
If the student prefers not to eat the gummy worm, he can use a plastic knife to cut off the segments.


NOTE: This lesson assesses estimating and measuring length to the nearest centimeter only.

Use completed Centimeter Slinkies Activity Log to formatively assess the student's ability to:

-use real-world objects to solve problems in estimation, and
-use concrete objects to investigate measurement of length.

The Centimeter Slinkies Rubric in the associated file includes the criteria for successful performance.


The following math journal activity can be used to encourage students to write about their observations.

1.Lead the students in retracing the steps they took while doing this activity and record them on the overhead. Teach signal words to show time order. Generate student responses as to what they learned, what they liked best about the lesson, what they liked least, and what they'd like to do differently if allowed to do this activity again.

2. Students then write a summary of the activity including their personal responses in their math journals (if they have them) or on a separate sheet of paper. Review strategies for writing a paragraph and stress the importance of using signal words to show time order. (Before students begin writing, share the assessment criteria for the summary.)

3. Invite several students to present their charts and summaries orally to the class.

The following rubric can be used to assess the math journal entries.

Summary in math journal or on notebook paper

-summary is written correctly in paragraph form, is meaningful, and accurately reflects the steps performed in the activity.
-the student correctly uses time order words in the summary.
-the student included his personal reflections about the activity and the responses demonstrate true reflection.

-summary is not written correctly in paragraph form, but is meaningful and mostly accurate.
-some time order words are used.
-the studentís personal reflections are weak or do not convey true reflection.
-the summary contains some error in time order of steps of the activity.

See Teacher:
-summary is not written correctly in paragraph form and does not accurately reflect the steps of the activity.
-few or no time order words are used in the summary.
-personal reflections are not included in the summary or do not demonstrate true reflection.

This activity can also be used as one of several measurement centers through which students rotate.
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