How to Introduce the Montessori Decimal Board: A Step-by-Step Guide Part 3
Earlier I talked a bit about how we can introduce the Montessori decimal board here (part 1) and here (part 2)
In the last section of Part 2 the lesson was on the student exchanging say 12 tenths for one whole and two tenths to make 1.2.
The Lesson: Making larger numbers on the decimal board
The next step is to ask the student to make bigger amounts on the decimal board
You can do this a number of ways for example the below amount could be made by asking the student to do one of the following
- Make three wholes plus four tenths plus six thousandths plus three ten thousandths
- Make 3 + 4/10 + 6/1000 + 3/10 000
- Make the number that is one whole more than 2.4063
- Make the number that is one tenth more than 3.3063
The Lesson: Rounding numbers
Dependent on where you are students may be familiar with rounding due to the currency you use for example $3.46. You could ask them whether 3.4 is closer to 3 or closer to 4. Having a number line to illustrate is really helpful along with making the number on the decimal board. When students are becoming more confident this activity in the picture below is helpful
Now is a good time to give students lots of opportunity to practise everything they have learnt so far. These task cards are ideal and help students:
Convert simple fractions to decimals
Know how many tenths in a number
Convert simple percentages to decimals
Know how many tenths are in a number
Add decimals into tenths
Add decimals into hundredths
Round decimals
Know if a decimal is closer to one number or another
Know whether a certain fraction or decimal is smaller or larger
Know how many hundredths are in a number
Find a decimal number halfway between two numbers
The Lesson: Showing how decimals and fractions look in different notations
This is also a good time to reinforce how decimals relate to fractions by asking students to write or demonstrate a fraction or decimal in the other notation. This match up activity worked well in my class.
In addition having students order numbers on a numberline with decimals and fractions is really helpful. Here I made a giant numberline that went from nearly one side of the class to the other from 0.0 - 1.0. I marked it at every tenth. I then gave out a range of premade cards and students placed them on the numberline. We then turned the cards over and wrote the fractional number.
Explore the Full Montessori Decimal Board Series
This is the final part of my Montessori Decimal Board series. If your child or students need to revisit the earlier presentations, you can return to Parts 1 and 2 before moving into more independent work with decimal place value, fractions, rounding and operations.
← Part 1: How to Introduce the Montessori Decimal Board
Begin with the first lessons introducing decimal quantities, tenths, hundredths and thousandths.
← Part 2: Montessori Decimal Board – Fractions and Exchanging
Continue with fraction-decimal connections and learn how to exchange decimal quantities using the board.
Ready for Independent Decimal Practice?
Once children have explored these ideas concretely with the Montessori Decimal Board, independent follow-up activities can help them consolidate what they have learnt and gradually move towards abstraction.
- Montessori Decimal Task Cards – practise decimal place value, converting fractions and decimals, rounding, comparing decimal numbers and finding numbers between other decimals.
- Ordering Decimals on a Number Line – reinforce decimal magnitude by asking children to compare and order decimal numbers visually.
- Montessori Decimal Addition Task Cards – move from building decimal quantities to performing addition with tenths, hundredths and other decimal values.
- Montessori Decimal Subtraction Task Cards – practise decimal subtraction while reinforcing place value and exchanging.
Want More Decimal Follow-Up Work?
If you would rather have a wider selection of activities ready to use, explore the Montessori Decimal Fraction Operations Bundle . It brings together further decimal work so children can continue practising the concepts introduced with the Decimal Board.
You can also see where decimal work fits within the wider Montessori maths progression in my free Montessori Math Scope and Sequence for ages 3–12 .