Explaining Mathematical Reasoning
METAWith teacher prompting, explain and justify mathematical reasoning using drawings, number sentences, or words
Mastery Evidence
- Explain a solution strategy using a drawing or number sentence (e.g. 'I made ten first, then added the rest')
- Justify why an answer is correct by showing an alternative method that gives the same result
- Identify and explain an error in a worked example or a peer's solution
Assessment Prompt
“If you ask [child] "how did you work that out?", can they show you with a drawing or explain their steps in simple words?”
Prerequisites3
- Showing Your WorkinghardAges 5—6
- What the equals sign meanssoftAges 6—7
- Addition in any ordersoftAges 6—7
Show full prerequisite tree
- Showing Your Working hard
Age 6-7 explaining with diagrams/logic builds on age 5-6 showing and telling with objects
- Numbers up to 10 into pairs soft
Explaining part-part-whole decompositions exercises showing and telling
- Addition as combining or putting together two hard
Decomposing numbers into pairs requires understanding addition as combining
- How Many in Total? hard
Understanding addition as combining groups requires knowing numbers represent quantities (cardinality)
- One-to-one counting hard
Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
- Number bonds to 9 soft
Explaining how to find number bonds to 10 exercises showing thinking with objects
- Numbers up to 10 into pairs hard
Making 10 is a specific application of decomposing numbers into pairs
- Addition as combining or putting together two hard
Decomposing numbers into pairs requires understanding addition as combining
- How Many in Total? hard
Understanding addition as combining groups requires knowing numbers represent quantities (cardinality)
- One-to-one counting hard
Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
- Listening and responding soft
Explaining mathematical reasoning orally requires basic listening and responding skills
- What the equals sign means soft
Determining whether equations are true/false exercises evaluating and justifying
- Reading +, −, and = symbols hard
Deep understanding of = requires already being able to read and write number sentences
- Reading and writing numbers to 20 hard
Writing number sentences requires reading and writing numerals
- How Many in Total? hard
Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)
- One-to-one counting hard
Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
- Writing digits 0-9 hard
Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)
- Addition as combining or putting together two hard
Reading/writing the + symbol requires understanding what addition means
- How Many in Total? hard
Understanding addition as combining groups requires knowing numbers represent quantities (cardinality)
- One-to-one counting hard
Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
- Subtraction as taking away or separating hard
Reading/writing the − symbol requires understanding what subtraction means
- How Many in Total? hard
Understanding subtraction as taking away requires knowing numbers represent quantities (cardinality)
- One-to-one counting hard
Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
- Addition as combining or putting together two hard
Understanding commutativity of addition requires understanding addition
- How Many in Total? hard
Understanding addition as combining groups requires knowing numbers represent quantities (cardinality)
- One-to-one counting hard
Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
Unlocks2
- Teaching It BacksoftAges 7—8
- Justifying mathematical reasoninghardAges 7—8