Maths: Subtraction Unit

Over the next few weeks we will be revising, exploring and extending our thinking around efficient & different strategies to solve problems involving SUBTRACTION.  Having automatic recall of facts under twenty will be very helpful in this work.  It would be great for your child to be practising their recall of subtraction facts.

subtraction_five_minute_frenzy_18_001-tal2qg

We will also be ensuring that we understand how to apply strategies we used to solve addition to subtraction – we will need to carefully rethink a few of these.  A favourite will be using empty or open number lines to use the jump strategy.  This is a great way to demonstrate how to think flexibly about numbers.  It is also a great way to encourage mental calculations.

Addition Strategies

As we finished Term One we were consolidating and extending our understanding of a variety of strategies to solve addition equations.  We reviewed the use of the jump strategy and the split strategy.  These strategies involve us using lots of different thinking.  By the end of Year Four it is expected that students can : apply place value to partition, rearrange and regroup numbers to at least tens of thousands to assist in calculations and solve problems

The jump strategy uses an empty (or open) number line.  To use this strategy students must break one of the addends into parts to make it easier to add.  This strategy really encourages students to think flexibly about numbers and is a stepping stone to mental calculations.

The Split Strategy also requires students to think about place value.  One or both of the addends needs to be decomposed into useful parts to make them easier to add to each other. It can look like these examples…

photo4-2i4vj1e
Split strategy 2

 

 

 

 

 

 

 

 

Our focus has been on exploring strategies that allow for students to come to a solution in a way that makes sense to them – with many steps or fewer steps.  There is no one way to get to the answer.

Being able to add tens or hundreds onto a number is a really important skill for both of these strategies to work.  You might like to practise doing this quickly.  For example: 23 + 10, 56 + 30, 67 + 20, 123 + 100, 345 + 200, etc.

Here a few fact sheets that explain these two strategies to mums & dads:

Split Strategy-1r745tm

Empty Number line-2ch7qbl

Jump Strategy-2m02zk2

Can you show mum and dad how you can use these strategies? Which one do you like most? Which one do you think you need more practice with?

PLACE VALUE UPDATE

The Victorian Curriculum states that Year Four students need to be able to model, represent and order numbers to tens of thousands.  For the last two weeks this has been the focus of our Maths lessons.

We have had some great sessions using interactives to help consolidate and extend our understanding of place value.  We have focused on understanding that each digit in a number holds a place and has value:

We have also been practicing writing numbers in three forms:

Some students are finding it tricky to remember that at times zero has a very important job at holding a place despite having no value.(Zero as a place holder-1b3ql7d).  This is especially important as we read and write numbers that have 5 digits and more such 80 123 or 45 604.  It would be good to practice reading, writing and expanding these numbers at home.

A fun thing we did in class was watch a YouTube clip like this one:

Then randomly I would press pause and the number that was on the screen, students had to read and record the expanded notation for. Have ago at home…

You might also like to use some of these websites for further practice (especially if you are having trouble with Studyladder)

http://www.math-play.com/Place-Value-Millionaire/place-value-millionaire-game_html5.html 

http://www.ictgames.com/caterpillar_slider.html

http://www.sheppardsoftware.com/mathgames/placevalue/BPOrder1000.htm

http://splash.abc.net.au/res/i/L1999/index.html

Our next unit is focusing on ADDITION Strategies.  You could practice up on your quick recall of basic number facts like 4 + 5, 9 + 9, etc.

🙂 Miss Morse

Mulitplication Posters

I just made a poster showing all the ways a multiplication fact can be represented:

FullSizeRender (3)

I would love you to make a poster for a different fact and bring it to school so we can make a display. How many posters will we get?

2016 2MS Potato Olympics

We have commenced our investigation into MEASUREMENT with the Potato Olympics.  Each coach created a Spudlete, which competed in three events.  Each event helped us to discover that when you measure you need to use a specific tool and each measurement has a name.  We measured weight in grams, on scales.  We measured distance (length) in centimetres, using a measuring tape.  We measured time in seconds, using a stopwatch.  We also had a lot of fun exploring and some laughs together…

Can you practice doing some measuring at home? Have you got some kitchen scales? Have you got a watch? What other measuring tools can you find around your house?

Are you practicing multiplication at home?

We have discovered that there are many ways to show a multiplication fact: equal groups of, repeated addition, an array, and a number sentence (which has a turn around fact).

Here are some examples so mums & dads know what the different ways look like…

Screen Shot 2014-11-03 at 1.51.35 PM

3-multiplication-and-repeated-addition copymultiplythree-multiplication-expression-for-equal-group

Remember the first number in the fact represents how many groups (or how many times we have to add, or how many rows there will be) and the second number is what we are counting by (or adding repeatedly or will be in each group or in each row). Good luck!

Rio 2016

downloadThis week we have an Olympic theme to our Daily Five activities.  It has already been an exciting start to the 2016 games. I wonder what sports you are looking forward to watching?

You might like to keep track of the medal count: http://rio2016.olympics.com.au/medal-tally 

Pick a day and complete this challenge:

If Gold=3 points, Silver=2 points, Bronze =1 point…

How many points do the top 5 teams have?

Explain how you worked it out.

Our Inquiry unit this term has been called “Dare to fail and to succeed.”  I wonder if this applies to the athletes participating in the Olympic games? What can we learn from the athletes about having a growth mindset?

Multiplication Magicians

We are exploring MULTIPLICATION. 

multiplication-3a

Before we learn to recall time table facts, it is important that we understand that multiplication is about:

  • Equal groups
  • Counting patterns
  • Repeated addition

We also have just discovered that multiplication has a commutativity property just like addition.  For example 2 groups of 10 is 20 and 10 groups of 2 is also 20.  The total is the same but what we count by & how many times we count changes.

Can you practice making some groups of (lots of, fish tanks of, baskets of, vases of) at home?

You could check out this website: Making groups of

This will help you start to see how to show groups on grid paper and using arrays.

Mums and dads might like to read theis handout to refresh their memories about groups and arrays:

Making groups and arrays