Year 2 – Jeanelle Attard and Joanne Vella
Learning Outcome:
B.2.8 use the following Mental Strategies:
i) use knowledge that addition can be done in any order to do mental calculations more efficiently.
ii) identify near doubles, using doubles already known.
iii) add 9 to single-digit numbers by adding 10 then subtracting 1.
iv) use patterns of similar calculations. e.g. 10 – 0 = 10, 10 – 1 = 9, 10 – 2 = 8
v) use known number facts and place-value to add or subtract a pair of numbers mentally within the range 0 to at least 10, then 0 to at least 20.
vi) bridge to 10, when adding a single digit number.
Previous Knowledge:
A.2.2 count on and back in steps of 1s, 10s…
B.2.6 know by heart all pairs of numbers with a total of 10; e.g. 3 + 7 and their corresponding subtraction facts.
(Show tens frame resource and ideas how to use it)
B.2.7know by heart addition doubles of all numbers to at least 5
Success Criteria:
  • I can add 2 or more numbers in any order.
  • I can use concrete objects to add and subtract.
  • I can use facts to 10 to add or subtract mentally.

Vocabulary:
Add
Total
Count on / forward
Subtract
Take away
Difference
Count back / backwards
More/less
Larger/smaller
Equal to
answer
Make
Leaves/left
Pairs
Double/doubling
Near doubles
Zero
How many more?
Bridging to 10…20 / Resources:
  • Number cards 1- 9
  • Playing cards
  • Small whiteboards and markers
  • Double Tens frame
  • Caps/ counters
  • Playing cards
  • 2 dice
  • Maths vocabulary flashcards
  • Double Bingo game board
  • Double spinner
  • paper clip and pencil for spinner
  • two colors of game markers
  • Maths Journal
  • 1 to 4 Self-Assessment rubric

Lesson – Adding and subtracting 9 (mental strategy)
Mental Warmup - Pair up Game
Ask learners to take out a number card (1 – 9) secretly from the toolbox. When the whistle goes, learners are to show their number card and find a classmate with the number bond to make 10. If there is no match, learners are to change their number card.
Introduction: (Working in groups)
1.Ask learners to take out the playing cards, put them face down and reveal the top card. Each student is to add 9 to the number shown, write down the computation on a small whiteboard and explain the strategy used, to work the sum, to his peers.(If teaching mental strategy to subtract 9, use number cards from 10 to 20)
2.Ask members of the group to report to the whole class, which strategy was used by any of his/her group members.
3.Using the tens frame mat resource and caps, explain the mental strategy of adding/subtracting 9 to single-digit numbers by adding 10 then subtracting 1/adding 1.
4.Once students have mastered the concrete level of adding/subtracting 9, introduce appropriate drawing procedures where students problem solve through drawing simple representations of the concrete objects they previously used.
5.Have students work in pairs. Using a deck of cards (excluding K, Q, J) ask students to reveal a card each, add nine to it and who gets the bigger answer wins both cards. Explain that if it is a tie, cards are to be shuffled back in the deck of cards.
Hinge Point Question:
If 10 add 4 equals 14, then 9 add 4 is equal to…?
  1. 12 B. 13 C. 15 D. 16
Journal
Word problem ideas (word doc)
______
Lesson - Addition using known double facts
  1. Mental warm-up
Children to practice double facts using the ‘Double Bingo’ board game. Player A spins the spinner and finds the double of the number the paper clip lands on. Using one colour of the game markers, Player A covers the answer on the Double Bingo game board. Player B then spins the spinner, finds the double of the number spun, and covers the answer using the other colour of game markers. Players continue taking turns doubling numbers and covering numbers. If a player cannot cover a number on the game board, her/his turn is over. The first player to have 4 game markers in a line (horizontally, vertically or diagonally) is the winner.
  1. Introduction (Whole Class Activity)
Same activity as in the online video accessible online at:
Or
Ask students to produce any double on the tens frame and generate a number sentence that goes with it on their personal whiteboard. Following this, ask students to share their observations about it ex: all counters have a partner, even numbers, 4 more to make 10…
  1. Explain to your class that at this stage, they are going to work with near doubles (the doubles’ neighbours) that is, one more than the double. Ask students to add one counter to the tens frame. Give enough time for students to think and discuss the difference when it comes to the total number of counters on the tens frame and why. Help children generate a number sentence on the personal whiteboard. Use 3 or more different representations to teach the mental strategy of adding near doubles.
  1. Hinge point question:
For which ONE of these sums I could use the near doubles strategy to work it out?
  1. 6+4 B. 5+5 C. 3+1 D. 6+7
  1. Have students work in groups/pairs the ‘Double Down’ Game using two dice. (instructions given on game sheet)
  1. Connecting Maths to other Subjects (physical education)
Explain to the Students that they are going to work in groups. When the whistle goes, students are to run around in the playground and gather flashcards printed on the coloured paper assigned to their group. When all flashcards are collected, as a group students need to discuss which strategy is the most appropriate to work out the sums gathered and later sort flashcards under three main headings: Making 10, Doubles and Near Doubles.
Create paths, with the same coloured Addition flashcards used in the previous activity, for children to follow (repeated paths so as to reduce waiting time and have more students on task at once). Ask the first child in the line to walk, crawl, jump or hop etc… along the path of mixed addition flashcards. Every child, in order to step onto the next card, s/he needs to work the sum correctly. If s/he fails to give the correct answer, s/he should move a step back and continues the game. The winning team is the group that finishes first. Every group should have a referee (chosen by the teacher) to check whether answers given are correct or not.
  1. Problem Solving
Addition Word Problems (pdf)
  1. Journaling
Give a prompt to the students such as: How can I work out 4+5? Following discussion about doubles and adding/subtracting near doubles (neighbours) students should be able to work out this addition sum using the tens frame (as pictorial) and use the near doubles mental calculation strategy for computation.
Later, students match doubles and near doubles pictures and number sentences in their Maths Journal and then cut out sets of doubles and near doubles flashcards so they can practice these facts from time to time.
Form of Assessment:
Pupils’ self- assessment using popsicle stick smileys
smiley faces fans
1 to 4 rubric