# The Part Adder

Students work out how to break up numbers so they can calculate addition mentally. Students use a linear model and part-whole relationships to find their answer.

### Teacher notes

• A partitioning model is shown so students can see the effect of breaking up numbers to solve a problem using known facts.
• The animation at the commencement of the learning object demonstrates some of the strategies, which are also available as 'hints' while students work.
• Strategies include: 'tens and ones' (where students add the 'tens' and the 'ones'); 'doubling' (where students focus on their knowledge of the two times multiplication table); 'make a ten' (where students break up one or both numbers so they are adding to a multiple of ten) and 'compensate' (where students can make one number larger and subtract the number they have added on).
• The printouts show how the student solved each equation.

### Learning objects

 The part-adder: generate easy sumsStudents solve problems that add a single-digit number to a double-digit number. The part-adder: make your own easy sumsStudents create their own sums, adding a single-digit number to a double-digit number. The part-adder: generate hard sumsStudents solve problems that add together two double-digit numbers. The part-adder: make your own hard sumsStudents create their own sums, adding together two double-digit numbers. The part-adder: go figureThe 'go figure' learning object is a tutorial that covers the various strategies briefly explained in the learning objects. It is amenable to a screen reader. The part-adderThis is an aggregated learning object combining the five other learning objects.