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HOW MANY LEMONS DOES IT TAKE?
by April Olson
University of Idaho

ITV SERIES The Challenge of the Unknown

GRADES 5 - 7

OVERVIEW

Students will discuss and learn about different methods that can be used to estimate from the video. Students will then practice estimation skills by recreating a sample problem from the video. Web sites containing other estimation activities are included.


LEARNING OBJECTIVES

  • Students will be able to identify estimation problems in every day life.
  • Students will practice estimation skills by recreating a Transect Sampling.
  • Students will be introduced to characteristics of Lemon Sharks.

FOCUS FOR VIEWING

Students need specific responsibilities while viewing the video. Hand out the "Am I Close?" focus-video guide and read over with the students. Tell them these are the things they want to watch closely for in the video.

However, they do not need to write the answers down as they hear them. The video will be paused several times, during which students will discuss answers and have time to write.

Also, tell students not to worry about the questions on the back of the handout; they will be dealt with later.

 

MATERIALS

  • Challenge of the Unknown teaching guide and video series
  • Copies of the "Am I Close?" focus-video guide for the class
  • "A Fact Sheet on Lemon Sharks"-included in teaching guide
  • "Comparative Size" chart-included in teaching guide
  • Overhead of Question 4 from the "Getting Started: Thinking Estimation" worksheet-information available in teaching guide(need to make into overhead)
  • Overhead of the Bimini Islands drawing, taken off of "Transect Sampling: A Birds-Eye View"-information available in teaching guide.
  • Masking tape
  • Goldfish Crackers
  • Lesson will take approximately 60-70 minutes-depending upon how much time is spent on discussion questions. May split into two sessions if needed

PREVIEWING ACTIVITIES

Discussion
The teacher will introduce the lesson by posing an estimation problem.

Put up overhead of question #4 (triangle problem) and write the students estimations on the chalkboard.
Then ask them to count the actual number of triangles and decide if they made good estimates. *Answer: 80 triangles

Ask students if they think it is always easy to estimate. Can they think of some things that might be hard to estimate? Do they think it is possible to have to research a problem before estimating? Why?

Ask if anyone has heard of Lemon Sharks. If so, what do they know about them? Then, (as a class) read over "A Fact Sheet on Lemon Sharks" and then show the "Comparative Sizes" chart.

Ask students what they can tell you about Lemon Sharks when comparing them to others.

 

VIEWING ACTIVITIES

The tape needs to be set on the first segment, "One If by Air. . .Two If by Sea," of the video section, "Estimation: Am I Close?"

PLAY the video. PAUSE right after the narrator says, "Lemon Sharks" (Visual: Samuel Gruber is hooking his ultralight to the boat). Ask students what Samuel Gruber's profession is. Discuss what a marine biologist is and what they do. *Ask students if anyone has heard of the name of the lagoon-Bimini Lagoon-write the name on the board. Ask if they remember where Bimini Lagoon is located. What state is it by? Then show students Bimini Lagoon (near Florida) on a map.

RESUME the video. PAUSE right after narrator says, "He still needed an accurate survey of the whole lagoon." Ask students if they can explain the tag-and-recapture method. Then ask why this method wasn't accurate for Gruber's estimation.

RESUME the video. PAUSE right after narrator says, "In his ultralight Gruber can easily cover the whole lagoon." Ask the class what is an ultralight and what does it do? Do they think Gruber will have better luck using the ultralight to make an estimation than he did with tag-and recapture?

RESUME the video. PAUSE right after the narrator says, "strip by strip" (Visual: aerial picture of lagoon being shown on screen). Ask students what system Gruber uses to survey the entire lagoon with the ultralight.

RESUME the video. STOP the video after narrator says, "Two educated guesses are better than one." Ask students if Gruber's survey of the Lemon Sharks by air was problem free. Why or why not? Then ask the class why they think Gruber decided to use two methods instead of one. Do they think this helped him make his estimation more accurate? Why?


Post Viewing Activities

(5-10 minutes) Classroom Discussion: As a class, discuss the questions on the back of the "Am I Close?" handout. (20-25 minutes) Students are going to try out the transect sampling method by recreating Gruber's situation from the video. Show the overhead of the Bimini Islands drawing from the "Transect Sampling: A Bird's-Eye View" activity sheet.

Point out that the transect strips are shaped like rectangles. Tell students that they are going to pretend the classroom is the Bimini Islands and lagoon. We have to estimate how many lemon sharks are in the lagoon. We will be surveying the area by air using the transect method. In order to carry out the survey the water must be divided into transects. Tell the students they can work together and do this by using tape.

*Note: If the floor is already divided by wooden beams or linoleum squares they can be used instead of tape. Before students start working, the area that represents the lagoon must be defined. Also, for this project, students will need to create 20 transects. After the students have finished sectioning off the "water" disperse the goldfish crackers onto the floor (not evenly). Next, students will take 5 of 20 transects and count the goldfish in each transect. Any goldfish that are on the lines between transects should be counted as part of the transect they are "swimming" into.

From this information, have the students make individual estimations (record them) of the total number of goldfish in the "lagoon." Then actually count the goldfish. How close were their estimations? Repeat the experiment, this time count the fish in 10 transects. Were the estimations closer than before?

Afterwards pull the students together for a discussion. What did they learn from this? Was it better to count more transects? Did it give them a more accurate estimation? What does this tell them?

 

 

ACTION PLAN

Students can start an Estimation Journal. The first page should consist of a list of all the possible things a person could use estimation skills for. Students should write in their journal (every day) about all of the estimation they participated in that day.

The journal will help students see how often they actually use estimation and how important it is to practice their skills.

Students should also be encouraged to bring in things the whole class can estimate. Example: Jars filled with something unique.

If you are interested in finding more estimation activities you might want to check out these web sites: (for a variety of grades)

www.portlandschools.org/Pages/LResults
/CS/Math/Key2.html

http://www.iit.edu/~smile/ma9407.html

EXTENSIONS

There is another great activity listed in The Challenge of the Unknown teaching guidebook. The activity is located on page 212 and is entitled, "Tag and Recapture in the Classroom." This is a fun activity that allows students to practice using estimations. It is similar to the activity above but it recreates a tag-and-recapture scenario.

Give students the opportunity to practice estimation in all of their subject areas. For example, have students estimate how long they think it will take them to read a specific story or how many words are on a page in a textbook. Students can also engage in estimation using "everyday" aspects of life. They can estimate how long it takes them to brush their teeth or how many fries are on their plate. Hold a brainstorming session and let students come up with things they can estimate.

 


For additional lesson plans and ideas relating to this topic and many others try TeacherSource at PBS Online! You will find activities, lesson plans, teacher guides and links to other great educational web sites! Search the database by keyword, grade level or subject area! Mathline and Scienceline are also great resources for teachers seeking teaching tips, lesson plans, assessment methods, professional development, and much more!


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