Math // Addition & Subtraction
Fluent addition and subtraction
Recall and use addition and subtraction facts to 20 fluently, and derive and use related facts up to 100
Quick check
Can the learner quickly recall facts like '9 + 7 = 16' and '16 − 7 = 9', and use those to help work out bigger sums like '90 + 70'?
Ask this to see whether the topic is secure.
Topic // Mastery
What mastery looks like
- Rapidly recall 7 + 8 = 15 and 15 − 8 = 7
- Use 6 + 4 = 10 to derive 60 + 40 = 100
- Derive 35 + 5 = 40 from knowledge that 5 + 5 = 10
Topic // Map
Where this fits
- RequiredMust come first
- HelpfulHelps, but not essential
Before this
2 topicsAddition & Subtraction // Ages 6 to 7
Fluent recall of facts to 20 builds from strategic calculation within 20
Number Representation & Place Value // Ages 6 to 7
Deriving facts to 100 benefits from place value understanding
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Fluent addition and subtraction
Ages 6 to 7 // Method
Leads to
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Topic // Research-informed
Teaching notes
From the Marble Skill Taxonomy. These notes have not been validated in classrooms, so treat them as a starting point for your own judgement.
The approach
Two linked goals for ages 6–7: automatic recall of addition and subtraction facts to 20 (so 7+8 and 15−8 come without calculating) and derivation of related facts to 100 by scaling and using known bonds — 6+4=10 → 60+40=100 by scaling the bond to tens, and 5+5=10 → 35+5=40 by using the ones bond inside a larger number. Recall is built from a secure make-ten strategy plus spaced, untimed retrieval rather than speed drills; derivation is built by treating tens as units so a known bond reappears at a larger scale.
Common misconceptions
- Recall not automatic — still counting on fingers every time for 7+8
- Failing to scale the bond: knowing 6+4=10 but giving 60+40=10 or 70 or 700
- Treating addition and subtraction as unrelated, so 15−8 is re-counted despite knowing 7+8=15
- Applying a derived pattern blindly (e.g. 35+5=40 but then 35+50=40)
Useful representations
- Ten-frame / double ten-frame (make-ten)
- Fact-family triangle (shows the three related facts)
- Bead string / Rekenrek
- Base-ten ten-rods (scaling a bond to tens)
- Number bonds part-whole diagram
Teaching practices
- Build automaticity from strategy, then retrieval: secure make-ten within 20 first, then space low-stakes recall practice so facts move to memory (DfE: emphasis on practice aids fluency)
- Teach fact families so + and − are learned together (7+8=15, 15−8=7, 15−7=8) and the inverse is available
- Derive decade facts by scaling a known bond: 6+4=10 becomes 60+40=100 because six tens plus four tens is ten tens
- Use the same visual at two scales (ten-frame counters vs ten-rods) to show 6+4 and 60+40 are one picture
- Avoid timed pressure that induces anxiety; keep finger/strategy use welcome while retrieval matures
Activities to try
- 1
Same bond, bigger units: scaling 6+4 to 60+40
Why it works: Deriving a decade fact like 60+40 is scaling a known bond, not memorising a new fact: six tens plus four tens is ten tens = 100. A different move is using a bond inside a larger number — 35+5 uses the ones bond 5+5=10 to give 40. Which unit you add (ones vs tens) decides the result, so 35+5=40 and 35+50=85 are different.
- Complete 6+4 on a ten-frame by sliding four counters in to fill all ten; confirm this is a known, secure bond making 10.
- Switch the counters to tens: let each counter become a ten-rod (or restate each counter as 'one ten') so the same full frame now reads 100.
- Say aloud what changed: 'six tens plus four tens is ten tens, which is 100' — the gesture and picture are identical, only the unit changed.
- Repeat the tens-scaling with another known bond: 5+5=10 → 50+50=100 (five tens plus five tens is ten tens).
- Separately, derive 35+5 by using the ones bond 5+5=10: 30 + (5+5) = 40, so here the 5 is added as five ones, not scaled to tens.
- 2
Fact-family triangle: one trio, both operations
Why it works: Addition and subtraction are the same relationship between three numbers; knowing one fact hands you the inverse, so 15−8 need not be re-counted once 7+8=15 is known.
- Lay out the three numbers 7, 8 and 15 on a fact-family triangle (part–part–whole).
- Cover one corner and read off the fact it reveals: cover 15 to get 7+8=15 and 8+7=15; cover 7 to get 15−8=7; cover 8 to get 15−7=8.
- State explicitly: because 7+8=15, you already know 15−8 and 15−7 without re-counting.
- Build a second family (e.g. 6, 9, 15, giving 6+9=15, 9+6=15, 15−6=9, 15−9=6) and name all its related facts the same way.
- 3
Spaced, untimed retrieval to build automatic recall
Why it works: Automaticity grows from secure strategy plus spaced, untimed retrieval; a fact becomes 'known' when recalling it needs noticeably less effort on later encounters.
- Practise recalling facts to 20 in short, low-stakes sessions spread over days (e.g. 7+8, 15−8, 6+4, 9+4), rather than one long timed drill.
- Mix in derive-a-fact prompts such as '6+4=10, so 60+40=?' and '5+5=10, so 35+5=?', choosing or writing the answer.
- After each prompt, say which ones you just knew and which you had to work out.
- Keep finger and make-ten strategy use welcome; the aim is that repeated facts need less effort each time, not beating a clock.
Topic // Standards
Curriculum standards
- The national curriculum in England: Key stages 1 and 2 framework document
- Maths/Y2/AS/3
Math // Addition & Subtraction
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