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1 There are nineteen monkeys
in the rain forest. Ten monkeys Problem-Solving questions 1 and 2 include:
left to climb trees. How many
monkeys are left? • Finding 1 less and 10 less than a given number mentally
9 monkeys • Solving word problem and situations concerning 1 less and 10 less than a
given number
2 I am ten less than 110.
What number am I?
Now, make your own clue. After children solve the independent practice, make sure they understand how
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Answer will vary. Sample an- to find 10 less than 2-digits numbers in real-life situations by solving problem 1.
49 is ten more than me. swer: I am 10 more than 56. Encourage them to read the situation carefully and guide them to use the 100
What number am I?
What number am I ? 66 chart to find 10 less than 19. The answer is 9 monkeys.
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Then have children explore a situation that includes making an inference and
justifying the answer using their own words in problem 2. Encourage children to
Vocabulary Check Complete. Write 10 more or 10 less. read and understand the problem carefully and then think about how to find
ten less and ten more than 2-digit numbers. Guide them to use the 100 chart to
find the numbers. Ten less than 110 is 100, and 10 more than 39 is 49.
10 more than 107 is 117.
After solving exercises 1 and 2, copy theadditional problems below onto the
10 less than 107 is 97. board for group or individual work. The additional problems are based on
finding 1 less and 10 less than a given number. Ask: How do you find ten more
than a number? and How do you find ten less than a number? Encourage
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children to use the 100 chart to find the numbers in each case.
Vocabulary Check If children have difficulty, give them a hundred chart and guide them to use it
to find ten less and ten more than a given number to solve the problems.
If children cannot complete the activity, use
a hundred chart to solve the problems. Additional problem 1
There were 61 students in grade one signed up to go on a field trip to the sea. 10
students decided not to go on the trip. How many students will be going on the
trip?
We can use the hundred chart to find 10 less than 61. We can find it by moving
EXIT ACTIVITY one step up, and then we have 51. There are 51 students going on the trip.

Additional problem 2
Use the Exit Activity for this lesson to Nathan has 70¢. He bought a candy for 10¢. How much money does he have
reinforce children’s understanding. This left?
can be used as an informal formative We can use the hundred chart to find ten less than a number We start with 70,
assessment. then move one step up to find 10 less than 70, which is 60. He has 60 cents left.

CLOSURE

At the end of the lesson, make sure children understand the main concept of the lesson by asking them to complete the
following: 10 less than 32 is _____

Children can use the hundred chart to find the number that is ten less than 32 by moving up one step. If we move one step up,
we get 10 less than 32, which is 22.

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