Reading and Writing with decimals

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SWBAT read and write decimals in standard form.

Big Idea

Knowing how to read and write decimals is a life skill.


10 minutes

The students will be re-visiting a prior day’s learning by modeling decimals 4 different ways.  They should be able to work on this independently without any difficulty.  Allow students to use 10 x 10 grids and base 10 blocks instead of having them draw them out.  Students can share their solutions with a partner and discuss any differences. (SMP 3)


10 minutes

There are two vocabulary words for this lesson:  standard and word form.  The students will use these vocabulary words throughout this lesson.  For standard form, I give them the example that standard means regular.  So, how do we normally see decimals? (Money, measuring, numbers).  For word form, I tell them it is exactly what it means.  The decimal is written out in words where the word AND indicates decimal placement. (SMP 4)

Writing numbers in word form

20 minutes

Students will be looking at several decimals.  Each slide has them looking at the standard form and then writing it out in word form.  I’ve chosen decimals that are easy to do and some that are more difficult.  Typically, the decimals that have zero’s as placeholders give the students some trouble.  Remind them that decimals are similar to whole numbers in that they are said the same way except that the place value for the decimal is the last words you hear.  So, if you hear thousandths, then the last digit needs to be in the thousandths place. 

Go through a few problems together, then have students work out their solutions on a white board and you can check for understanding with the whole group.

Common misconception:  students like to use AND when dealing with larger whole numbers.  This needs to be addressed because it is an incorrect way of reading and writing whole numbers and decimals.  The only AND we should see is where the decimal is located.  I also like to make a place value chart and laminate it so the students can use it to keep track of their place values.  They can also use a plastic sleeve and keep it in their binders for future reference.

Standard Form

20 minutes

The hardest part of writing decimals in standard form is knowing where your last digit is going to be placed.  When I’m teaching this part, I have the students identify the place value. (SMP 2) For example:  three tenths.  I would say, what is the place value we need (tenths) then I would say the three needs to be in the tenths place.  If there are other values, then we can work backwards to put them in the correct place values. (SMP 4 and 6) 

Go through a few problems together, then have students use their white boards to show you their answers.  This way you can get a good idea of who is getting it and who is not.

For students that are struggling, have them use the place value chart.  For students that need more, have them come up with equivalent decimals and write it in word form. 

Memory Match Game

15 minutes

Students will be playing with a partner to complete a game called memory.  On each card there is a matching standard and word form.  The game starts with all cards face down.  Student A turns over two cards and decides whether or not they are a match (standard to word).  Student A needs to explain their reasoning for their decision (why or why not) (SMP 2, 3, 6) If student A gets a match, they can keep the cards.  If not, the cards are turned over and it will be students B’s turn.

Tools:  Memory match cards.


10 minutes

The students will be completing an essential question wrap up.  The purpose of this wrap up is to provide students with an easy way to organize what they have learned.  The students will be re-visiting their two vocabulary words and coming up with examples on their own to support their understanding of these concepts.  Before starting the EQ wrap up, have students do a think-pair-share to stimulate thinking.  Once both partners have shared their thoughts, have the students complete the wrap up. (SMP1,2,3,5,6)