- Home
- Canvas Guide
Partial Progress - Circles (browser only)
Addition and Subtraction
Objectives
To add and subtract 10 (using Spider).
Resources
Abacus Workbook 1 | Small plastic or toy spider | Two 1–9 dice
Vocabulary
ten(s) | multiple(s) of 10 | one(s) | add | subtract
Today's Lesson
Introduction
Look at the 📄 100 square with your student, and introduce the toy spider.
Explain that Spider moves up and down its thread. Spider helps us count in 10s by moving up and down the grid.
Place Spider on 8, and move her down the grid as you count on in 10s, 8, 18, 28… 98, asking your student to join in as they can.
Say, ‘Spider could work out 18 add 10 by counting in ones, but she doesn’t, she just moves down a square. She does this as it takes so much longer to count on in ones when you are using a 100 square.’
Show your student how long it would take to count on in ones from 8 to 18. Then show how quick it is just moving down 1 square on the 📄 100 square from 8 to 18. You land on the same number but counting like Spider is much quicker.
Start at 6 and count on in 10s like Spider. Repeat, starting from different numbers.
Then ask, ‘How do you think Spider subtracts 10? Yes, she moves up a square!’
Place Spider on 95 and move her up as you count back in 10s to 5. Say, ‘She’s subtracting 10 each time she moves back up the grid!’
Place Spider on 45. Ask, ‘What is 45 subtract 10?’
Repeat again with other 2-digit numbers, your student saying the number that is 10 less.
This video talks through using Spider to add and subtract 10 on the 100 square. It also goes over the activity below, where we write the calculations of +10 and –10.
Main Activity
Work with your student to roll two 1–9 dice to make a 2-digit number less than 90 but more than 10.
For example, if you roll a 5 and 3 you could make the number 35 or 53.
Your student should place their finger on that number on the 📄 100 square. Then they should ring the numbers above and below it.
Finally, they should write the corresponding number sentences.
For example: 62 + 10 = 72; 62 – 10 = 52.
Repeat this at least five times so that your student becomes more confident and quick.
Extra Challenge
Can your student find the missing number in these sentences?
4,14, [ ], 34,44
19,29,39, [ ], 59,69
22,[ ], 42,52
Can your student find 10 more and 10 less than these numbers on the 100 square?
18, 32, 65, 89
Workbook
To help your student build upon their learning from today, please ask them to complete the activities on page 38 of Abacus Workbook 1.