Stories in Stone (Rounding to the Tens Place)

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SWBAT round numbers between 0 and 1,000 to the closest ten.

Big Idea

Place value is the bedrock that everything is built on!

Note to the Teacher

I deliberately teach this lesson third in this unit, instead of immediately after the first lesson on rounding to the closest ten, because I want students to develop the habit of attending to the specifics of the rounding task.  

Their awareness of whether they are rounding to the closest ten or hundred shouldn't be based on, "We must be doing what we did yesterday."  Instead on the precise language embedded in the task... round to the closest ten or round to the closest hundred.

Initial Question - How Old Are These Rocks?

23 minutes

Show students the Stories in Stone images (with pauses or no pauses) of several different rocks and have them guess how old each one is.  As they have no basis for comparison, and as the scale of geologic time is vast, this is an extremely abstract question.  It's valuable as a hook because most of them haven't previously considered the idea that rocks can be dated, and are excited to know that not only can they be dated but they can tell us many stories about environments in the past. Have them record their guesses (one can not estimate w/out having a semblance of a reasonable guess) using Stories in Stone Entrance Ticket. The resources include a Stories in Stone Entrance Ticket Teacher Key

After everyone has made a guess, reveal the real approximate age of each of the rocks.  Circulate to make certain students can write the numbers/ model the numbers on the board.

Explain that tomorrow we will be taking a virtual journey to Capitol Reef National Park in Utah where we will read some rocks.  They will use the ability to identify key information to answer some mathematical questions about the relative dates of the formations.  Additionally, they will apply their understanding of place value to work with numbers larger than 1,000. 

Guided Practice

14 minutes

Using a number line model, demonstrate how to round to the closest ten with numbers between 1-100, 100-1000 and 1000 and 10,000.After demonstrating one (or more if needed) example of each, have students draw an open number line and answer similar questions.

Teacher demonstrates how to round 17 and 58 to the closest ten.

SWBAT draw a number line model and round 42 and 85 to the closest ten.

Teacher demonstrates how to round 123 and 549 to the closest ten.

SWBAT draw a number line model and round 431 and 886 to the closest ten.  They will be able to use precise terms (closest ten, greater than, less than, one's place, ten's place, hundred's place, digit, number) to explain their thinking.  

Teacher demonstrates how to round 1546 and 4592 to the closest ten.

SWBAT draw a number line model and round 1243 and 9231 to the closest ten.

At this point, either place students into differentiated groups for independent practice based on teacher observation and their performance on the pre-assessment or let them self-select an independent practice level.

Strategies for Rounding

25 minutes

On-level students will be able to round numbers between 0 and 1000 to the closest ten.  Monitor them and depending on need, work with them in a small group. 

Small group suggestions: Rounding to Tens Group

On-level independent practice: Rounding to Tens Independent Practice

Students who have already mastered rounding to tens place with numbers between 0 and 1000 will practice rounding numbers between 1000 and 1,000,000 to the closest ten.  If these students truly understand how to get to the closest ten, they will be able to carry this skill into larger numbers.

Monitor students to see if they need assistance setting up the "start" and "end" points on their open number lines.  It may work well to write the number lines (with only the start and endpoints for each problem) on the board.

Rounding to Tens Independent Practice Enrich

Exit Ticket

5 minutes

This short Rounding to Closest Ten Self Assessment serves a dual purpose.  It provides me with possible additional information about students understanding of the topic and it gives them valuable practice in evaluating their own learning.  Metacognition is a skill that takes time to develop but activities like this are a start!

It can also be a useful barometer for overall classroom sentiment and understanding regarding a lesson, as well as a means by which a shy struggling child can communicate that they need further assistance.