Math Investigations

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Chapter 12

Part 1: For the problem in the Teacher's Edition, page 304

Provide students with the Problem Worksheet (PDF file)

Have students do research over the Internet and in books to find the record height for a sunflower. Have them write the source for the information they find.

Have students compare their results. Students will most likely find different results. Talk about how different sources can give different results when doing research. Talk about how you can even find wrong information when doing research and how you must be very careful to choose good sources. Talk with the students about the best kind of sources to use on the Internet. Examples of good sources might be:
  • government sites
  • university sites
  • sites for a city or state

If you do want your students to do research, have them find the metric equivalent of 25 feet. To convert feet to meters, multiply by 0.30. 25 feet is about 7 1/2 meters.

Part 2: Be an Investigator

A good time to do this investigation is after Lesson 7 on metric units of length.


  • pot, dirt, seed, water
  • rulers

Introducing the Investigation

Introduce the investigation by reading aloud the assignment at the top of the first page of the Description of Investigation and Student Report (PDF file), by having one of your students read aloud the assignment, or by having the students read the assignment individually.

Tell students that they are going to be growing a plant and keeping track of what happens to the height of the plant over time.

Put students in groups of two to four to work on the investigation.

Doing the Investigation

Help students set up bar graphs to keep track of the height of their plant. Watch them as they measure their plant to make sure they are measuring correctly.

Look for the following when you read students' written paragraphs:

  • Whether the plant got taller over time.
  • How much the plant grew between each time it was measured.
  • When the plant grew the most and when the plant grew the least.

If you cannot have students grow a plant, have them look at the following bar graph that shows the growth of one plant. Have them write a paragraph about the growth of the plant over time.

plant growth graph.

Students should note that the plant got taller over time. They might report the difference in height from measurement to measurement.

Student Report

The Student Report gives students an opportunity to talk about what they found as they kept track of the height of their plant.

Extending the Investigation

Grow two different kinds of plants. Keep track of the height of each plant on a double bar graph. Compare the growth of each plant.

Houghton Mifflin Math Grade 4