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1 Laura’s parrot can say 30
words. Linda’s parrot can say Problem-Solving questions 1 and 2 include:
20 words. How many more • Subtracting tens using place value concept
words can Laura’s parrot say
than Linda’s parrot? • Solving word problems concerning subtracting tens
10 words
To reinforce children’s ability to subtract tens from multiple of tens in a real-life
2 I am thinking of a I am thinking of a Make your own
number. I subtract number. I subtract clue and ask your situation, have them solve problem 1. Encourage them to read the situation
1 ten from it. The 4 tens from it. The classmates to solve carefully and guide them to use the place value concept or counting back on
answer is 8 tens. answer is 4 tens. it.
What number am I What number am I the number line to subtract tens to find the difference between the numbers of
thinking of? thinking of? Answers will vary. Sample answer. I am words of each parrot. The answer is Laura’s parrot speaks 10 more words.
90 80 thinking of a number. When I subtract
Then have children explore a situation that needs using different strategies to
3 tens from it the answer is 30.
find the missing numbers in their own words in problem 2. Encourage children to
What number am I thinking of ? 60
read the problem carefully. Guide them to use count back or the place value
Vocabulary Check Match. concept to find the missing numbers in each case.

subtract tens 60 + 30 = 90 For more practice, copy the following exercises from the additional problems
on the board for group or individual work. The additional problems are based
add tens 60 − 30 = 30
on subtracting tens. In problems 1 and 2, ask: How can you subtract tens using
count back in tens?
Discuss with them the relationship between count back and subtracting. Discuss
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how subtracting tens is related to the place value concept. Encourage children
to recall counting back in tens and the place value concept to subtract tens in
Vocabulary Check each problem.
If children have difficulty, give them a place value chart, a number line, and
If children struggle to make the matches, some counters. Guide them to use count back in tens on the number line and
write the problems on the board and point the counters in the place value chart to solve subtraction problems.
out which uses tens and which uses ones.
Additional problem 1
Adam collected 50 apples from his grandma’s farm. His grandma took 30
apples and left the rest for him. How many apples are left for Adam?
We can use the place value chart to subtract tens from a two-digit number.
EXIT ACTIVITY The final answer is 20 apples; it is left with Adam 20 apples.

Additional problem 2
Use the Exit Activity for this lesson to There are 70 children in grade one, 10 are off sick. How many children are
reinforce children’s understanding. This there in grade one?
can be used as an informal formative We can use the count back on the number line to subtract tens. The final
assessment. answer is 60, it is left in grade one 60 students.

CLOSURE

At the end of the lesson, make sure children do not have any misconceptions. Say:
Use subtract tens to subtract 90-50
Tens Ones
Children can use the place value chart to subtract tens from a two-digit number. They will
subtract tens from tens (as 9 tens - 5 tens = 4 tens). 9 0
- 5 0
The opposite place value chart shows the answer. 4 0

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