Growing Bean Plants

Task

Materials

• 2 clear plastic cups for each pair of students
• 4 bean seeds for each pair
• soil
• unifix cubes
• a plant or math journal to record data in

Actions

1. Students in pairs grow bean plants from seed. Students should label the first cup with a A and the second cup with a B and write their names on the cups. Then they fill their plastic cups 2/3 full with soil and place two bean seeds in each cup about one inch below the surface of the soil. Water the seeds and place the cups on a window ledge where they will receive sun light. The teacher should grow several cups to be "class plants" and as backups.

2. The beans will sprout within 7-10 days. When the bean seeds start to grow, choose two plants to be the class plants. Every few days, the class should water the plants. As a whole group, they measure the height of the class plants with unifix cubes. The first few times the teacher can do it, then the students can take turns measuring and recording the height in a table.

   

   The measurements should be recorded to the closest whole number.

3. Once students have done the measuring and recording as a whole group, the pairs of students can measure their own bean plants. They should measure the tallest plant in each cup if more than one bean sprouts. Students record each measurement in a table with the date in a math journal (or a plant journal for this project only if the class does not keep math journals).

4. After the students have measured their plants, they answer these two questions:

   • Which plant is tallest today?
   • How much taller is it?

5. On the last day of the activity, the students can compare the tallest plant in the room with the shortest plant.

IM Commentary

Growing bean plants is a common science activity at this age. This task adds some rigor to the activity, by collecting actual growth data, providing practice for students in measuring and recording length measurements. This task primarily addresses standard 1.MD.2

Express the length of an object as a whole number of length units, by laying multiple copies of a shorter object (the length unit) end to end; understand that the length measurement of an object is the number of same-size length units that span it with no gaps or overlaps.

The task also addresses 1.OA.1 by asking students to compare the heights of the plants. To see a version of this task that is appropriate at grade 2, see 2.MD Growing Bean plants, http://www.illustrativemathematics.org/illustrations/493.

Other suggested questions or discussion topics:

• Why is a specific bean plant taller than the rest, or shorter than the rest? Could it be due to different amounts of water, different light levels, or something else?

• How tall will the plants become? How could we find out the expected height (check the seed packet, look online, etc.)?

Possible extensions

1. In addition to measuring and recording plant height, students can also count and record how many leaves their plant has on each date.

2. As a writing extension, students can write and draw about their plant's growth. If students do this they should date each entry and write "like a scientist," recording their observations about how the plant changes as it grows. Students can look at root growth, how bushy the plant gets, if the stalks are curly or straight, etc.

3. Additional plants can be placed in a corner or closet to allow for additional discussion and comparisons.

Solution

There will be multiple correct solutions to this activity as each plant will grow at a different rate. Teachers should look to see that each student has correctly recorded the date and measured the height of the bean plant accurately and then recorded that number in their journal as well as a drawing or equation that answers the comparison question.

March 11

$$7+?=11$$

Plant A is 4 inches taller than plant B.