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# Introducing Decimals and Simple Decimal Addition

### Collection Developed by:

Collection Credits

### Collection Funded by:

Funding for the VITAL/Ready to Teach collection was secured through the United States Department of Education under the Ready to Teach Program.

## Resources for this Lesson:

Connections

Everyday Math (2004)
Teacher Lesson Guide, pp. 202-227
Student Reference, pp. 24-35
Math Journal pp. 80-84, 88
Math Master, p. 269

Investigations/Scott Foresman (2006)
Money, Miles, and Large Numbers
Investigation #2, Session 1-4, pp. 30-45

Standards

to:

Not yet reviewed.

### Overview

Students are asked to recognize the equivalence of fractional tenths and decimals, and to do simple decimal addition to find lengths both shorter and longer than 1. This CYBERCHASE activity is motivated by video clips in which the CyberSquad is trying to make repairs to railroad track that Hacker keeps sabotaging. The tracks are measured in decimal lengths, so the CyberSquad has to find out how to add decimals to get the lengths they need when they replace missing rails.

3-6

1 hour

### Media Resources

10th's and Decimals QuickTime Video
Several Short Rails Make More Than A Whole QuickTime Video

### Part I: Learning Activity

1. Have students work in pairs to complete the activity.

2. Tell students that they will watch a video clip that shows how fractions in tenths are equivalent to decimals, and that decimals are added similar to whole numbers. No contextual framing is needed as it is in the clip.

3. Show the students the 10th's and Decimals QuickTime Video .

5. The handout first demonstrates equivalence of a fraction and a decimal in tenths, and asks students to locate a decimal when given a fraction, and vice versa, on a number line and on a hundreds chart.

7. The handout demonstrates how decimals can be expressed in 100th's as well as 10th's, and then asks the students to locate a decimal when given a fractional in 1/100's, and vice versa, on a number line and on a hundreds chart.

8. Tell students they will watch a video clip that shows how decimals can be added and how one decides where to place the decimal point.

9. Show the Several Short Rails Make More Than A Whole QuickTime Video . Emphasize that it is important to remember that the fractions in tenths are equivalent to decimals with one decimal place.

### Part II: Assessment

Assessment: Level A (proficiency): Students are asked to add the lengths of 4 bars of different decimal lengths, and then to draw the total length on a number line. The sum is greater than 1.

Assessment: Level B (above proficiency): For the growth in height of 3 different children, students are asked to add the growth to find the total growth for the 3 children.