I need some help with teaching decimals. I plan on introducing the concept to my students next week. I've been putting this off because I'm dreading it! Every time I open up the lesson in the math book, I cringe, ha!

We've already learned fractions. Next, we need to relate the fractions to decimals and explore tenths and hundreths.

I don't have a sure fire way, but I think we're getting there. First, I put the attached document into a clear sleeve and gave my kids dry erase markers. We marked a certain number of dollars, dimes and pennies and reviewed writing dollars and cents. We talked a lot about how dimes equal one tenth of a dollar, and a penny equals 1/100th of a dollar. Sometimes we wrote a dollar amount and then marked the money, but mostly we marked the money and then wrote the dollars.

The next day we made it more abstract by doing the same thing with another sheet - I'll attach it next. I colored in an amount and projected it so they could see it, color in the same amount, and then write the decimal to go with it. Sometimes, I'd write a decimal and they had to color in the right amount.

The biggest difficulty they have is understanding the difference between .04 and .40 when they have to write it on their own. It's also hard to hear the difference between "tens" and tenths" and even more between "hundreds" and "hundredths," so I articulate that to them a lot-and very clearly. They seem to get adding and subtracting pretty well as long as they know to line up the decimals.

Last edited by tangolily; 03-08-2012 at 03:13 PM..
Reason: spelling

I am using beaded shoelaces this year. Take a shoelace and tie a knot in one end. (The athletic laces work better than the flat "skater" shoelaces.) Use two colors of beads, ten of one color then ten of the other, alternating until you have 100. Tie a knot at the other end.

This is going to be hard to describe, but I will do my best.

Place value blocks have always worked best for me when teaching decimals. Each child will need a flat, ten rods, and ten cubes.

Build fractions on the flat beginning in the bottom left-hand corner. Work from bottom to top.

Give each child a flat.
--The flat will equal one.
--Each small square on the flat will equal 1/100 (one hundredth).
--Each rod will equal 1/10 (one tenth).
--Each small cube will equal 1/100 (one hundredth).

Have students show you 0.4 (four tenths).
--Students will take four rods and lay them on their flat.
--Students will write the decimal 0.4 (four tenths) or 0.40 (forty-hundredths).
--Students will write the fraction 4/10 or 40/100.
--It means four out of ten or forty out of one hundred.

Have students show you 0.54 (fifty-four hundredths).
--Students will take five rods and four cubes and lay them on the flat.
--Students will write the decimal 0.54 (fifty-four hundredths).
--Students will write the fraction 54/100.
--It means fifty-four out of one hundred.

Have students show you 0.25 (twenty-five hundredths).
--Students will take two rods and five cubes and lay them on the flat.
--Students will write the decimal 0.25 (twenty-five hundredths).
--Students will write the fraction 25/100 or 1/4.
--It means twenty-five out of one hundred or one out of four.

Have students show you 0.5 (five tenths).
--Students will take five rods and lay them on the flat.
--Students will write the decimal 0.5 (five tenths).
--Students will write the fraction 5/10 or 1/2 or 50/100.
--It means five tenths or one half or fifty one hundredths.

Model and practice, practice, practice over several days.

I am going to attach a decimal directory I made for my students. Don't use this directory until your students have done lots of practicing with flats, rods, and cubes. What I am attaching is not complete.
--Run the attached pages on white 8 1/2" x 11" paper.
--Fold three pieces of 8 1/2" x 14" paper in half. This will give you a twelve page book (counting the cover).
--The words "My Decimal Directory" go on the cover. You will literally need to cut out with a scissors and glue to the cover. Glue it the long way so it opens from top to bottom (rather than from right to left like most books).
--For page three, cut out with a scissors 0.08 and 0.1/0.10 boxes. Leave a white edge around the boxes. Glue these boxes to page three. You will also need to find a small picture of a flat to glue next to these boxes. Your students will use their pencil to shade in the flat picture to show 0.08 and 0.1/0.10. Again, you are gluing the long way so it continues to open from the bottom.
--Check the fraction column because there are no lines to show that the numbers are fractions. I just took a black marker and drew the lines before copying.
--Repeat the same procedure for the rest of the pages. This tool will be a great reference for your students to use when they are not sure what a decimal looks like.

I am going to attach "Exploring Decimals." Feel free to make other sheets like this one. It will get students into the habit of thinking about numbers less than one in a different way.

In the fraction column, you will need to add lines to 73/100 and 7/100 so they look like fractions.

Making decimal flashcards is very easy.
--Find a picture of a flat. (I used some flats that showed one hundred cubes (for hundredths flashcards), but I also drew one that showed ten rods (for tenths flashcards).
--Enlarge it so it is as large as you can get it on a piece of 8 1/2" x 11" paper.
--Run two dozen (or more) on white cardstock (some tenths and some hundredths).
--Shade them with colorful markers (one color for each flashcard).
--Remember to always color from the bottom to the top. (0.54 would be five columns colored from the bottom to the top and four cubes colored from the bottom and up four).
--This is a great SCOOT game. The student's answer sheet could have a column to write the decimal and a column to write the fraction.