Estimation strategies using website applets

This activity uses several applets that teach and reinforce estimation strategies. Shodor Education Foundation, Inc has granted permission for the use of the Shodor materials as part of the workshop- "Interactivate Your Bored Math Students."

A lesson plan for grades 3–4 Mathematics

By Bonnie Boaz

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Related topics

• Learn more about mathematics.

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Learning outcomes

Students will:

• compare two amounts using the terms:
  • Greater than
  • Less than
  • Almost the same
• determine if the pictorial representation is Greater than or Less than the numeral.
• Given a pictorial representation of an amount, students will estimate numerically within a 15% tolerance.

Teacher planning

Time required for lesson

3-4 hours

Technology resources

• Color monitor with access to the internet for each student
• (Optional) LCD projector for teacher

Pre-activities

Play some estimation games with the students before proceeding to the procedures. For example, bring a jar of jelly beans to the class. Ask the students if the jar contains more than one thousand jelly beans (no). More than two jelly beans? (yes). More than one hundred? (don’t know). Pass the jar around and have students estimate the number of jelly beans. Have a student count them out and see who is the closest to the actual number (may provide a small prize, or simply distribute the jelly beans to the class).

Activities

1. Using verbal directions or demonstrate with an LCD projector how the shodor.org website works. Review the directions with students clicking on the “How” button.
2. Students work alone or in pairs with the following applets (in order). Students should spend about fifteen minutes on each applet.
   • Comparison Estimator - Focuses on comparing two sets of objects using less than, greater than, and equal to.
   • More or Less Estimator - Focuses on comparing an image with a number estimate generated by the computer using greater than, less than, and equal to.
   • Estimator - Focuses on having the user actually enter in an estimation based on a computer generated image.
   • Estimator Four - focuses on helping students develop their speed and accuracy in answering addition, multiplication, and percentage problems. This applet accomplishes this by having the students compete against each other and against a timer in game modeled after connect four.
3. The first three applets use the strategy of using grids to divide the pictorial representation to make the estimate more accurate. Have students use the hint button to set-up a grid on their pictorial representation.
4. Many of the applets have settings to control:
   • Problem Type-random, counting, length, area
   • Difficulty-easy, hard
   • Tolerance-5%, 10%, 15%

   Problem type and difficulty are fairly straight forward in making choices and you should encourage students to make choices here. Tolerance is a fairly difficult area for 3rd and 4th grade students to understand. I would suggest that you ALWAYS have students put the Tolerance setting at 15%.

5. Estimator Four is an applet that uses more traditional estimation in computation to play a game with a partner that is similar to “Connect Four.”

Assessment

Use an end of unit test on estimation using problems of estimation of area, counting, length, and computation appropriate to your student’s abilities. Problem types should include: comparing two pictorial amounts, and comparing a pictorial amount with a number, using terms greater than, less than and almost equal. Other problem types should include estimating a pictorial amount with a numerical amount. In these three problem types grids should be expected. A fourth problem type should include estimation of computation with computation that is appropriate for your students.

Student should achieve 70% mastery on this assessment. If they achieve less than 70%, students should go through reteaching and the activities section of this lesson plan again. Then students with a beginning mastery can go through the activities at a harder level.