Model It & Explain It
2.4 + 1.3 =
Model and solve. What digit is in the tenths place of your sum?
The sum of 2.4 and 1.3 is 3.7
The digit 7 is in the tenths place of the sum.
2.4 + ___ = 5.4 — show on a number line. What is the addend?
3.0is the missing number, addend = missing number added.
You buy a drink for RM 2.50 and a snack for RM 1.75. Model with a number line. What’s the sum?
The sum of buying a drink for RM 2.50 and a snack for RM 1.75 is RM 4.25.
You buy candy for RM 1.25 and gum for RM 0.75. Model this addition. What does the decimal point represent in RM?
If I buy candy for RM 1.25 and gum for RM 0.75 the total cost would be RM 2.00.
The decimal separates ringgit (whole) and sen (part).
3.6 + 2.45 – 1.5 — model both operations. Which step did you solve first and why?
4.55; solved addition first, then subtraction
Model 4.2 – 1.5 using base-ten blocks. Explain which place value you had to regroup from.
2.7; regrouped from ones to tenths.
9.6 – ___ = 4.85 — model on a number line. How do you know your answer is reasonable?
If I use rounding to estimate I would round 9.6 to 10 and 4.85 to 5. 10-5 = 5. The actual difference is 4.75, this solution is close to my estimate so I know it's reasonable.
A pencil costs RM 0.85. You buy 2. Use an algorithm and describe what the decimal point shows in money problems.
The total cost of buying 2 pencils for RM .85 each is RM 1.70. The decimal separates ringgit and sen.
You have RM 5.00 and buy ice cream for RM 3.40. Use base-ten blocks to model your change.
If I buy ice cream for RM 3.40 with a RM 5.00 bill I would receive RM 1.50 in change.
(2.5 + 1.5) × 2 =
Add inside parentheses first → 4.0 × 2 = 8.0
Use base-ten blocks to model 3.75 – 1.2. How many hundredths are in 0.75?
2.55; 75 hundredths = 0.75
6.7 – ___ = 2.3 — model and explain what the difference represents.
4.4; difference = the amount taken away.
You had RM 10.00 and spent RM 6.35. Model on a number line. What difference are you finding?
After spending RM 6.35 you will have RM 3.65, this is the difference between the total and the amount spent.
Three notebooks cost RM 2.35 each. Use repeated addition or algorithm to model the total.
If I buy 3 notebooks for RM 2.35 each I would pay RM 7.05 all together.
(5.2 – 2.2) × (3 + 1.5) =
3.0 × 4.5 = 13.5 (round to 13.5)
Show 2.45 + 3.75 and explain why lining up decimal points is important.
6.20; decimals must align so place values match.
___ + 3.45 = 7.25 — explain how to estimate to check your answer.
To estimae I would round 3.45 to 3.5 and I would round 7.25 to 7.00, my is estimate 3.5 + 3.5 ≈ 7.0 for a reasonablility check.
You walk 1.25 km to school and 1.75 km home. How far did you walk? What operation tells you the total?
If you walk 1.25 km to school and 1.75 km home, you would walk a total of 3.00 km. Addition is the operation needed to solve this problem.
A toy costs RM 8.95. You pay RM 10. What’s your difference and what operation did you use?
To find the differnece I would subtract RM 8.95 from RM 10.00 to get RM 1.05.
Use the order of operations to solve (4.8 – 1.6) × (2 + 1.5).
Then explain how PEMDAS helps you know which part to do first.
4.8 – 1.6 = 3.2 → (2 + 1.5) = 3.5 → 3.2 × 3.5 = 11.2
PEMDAS helps me remember to do parentheses before multiplication.
(3.6 + 2.4) ÷ 2 =
Model using a bar diagram or number line. Show how adding first changes the total before dividing.
Explain which operation comes first and why.
3.6 + 2.4 = 6.0 → 6.0 ÷ 2 = 3.0
___ – 1.8 = 3.2 — what’s the minuend, subtrahend, and difference?
Minuend = 5.0, a quantity or number from which another is to be subtracted
Subtrahend = 1.8, the number that is being subtracted from another number in a subtraction problem
Difference = 3.2, the result of subtracting one number from another
A rope is 12.5 m long. You cut off 3.75 m. Explain how subtraction is used to find the remaining amount.
If you cut 3.75m off a rope that is 12.5 m long, you would have 8.75 m remaining. Subtraction is used to find the remaining amount.
A book costs RM 14.75. You get a RM 2.60 discount. Explain what the word “discount” means in math terms.
After the dsicount the new price would be RM 12.15.
Discount represents the amount subtracted from original price.
(7.5 – 2.5) ÷ (1.25 + 0.75)
Numerator = 5.0; denominator = 2.0 → 5 ÷ 2 = 2.5
5.0/2.0 = 2.5