1.
A clinic gives out 128 doses a day for 7 days. At the end of the week 96 doses come back unused. How many doses were actually used?
SHOW YOUR THINKING
Answer:
Did you know? A vaccine is a practice run. It shows your body a harmless piece of a germ so the real one is already familiar.
2.
A nurse packs 75 vials into cool boxes. Each box holds 8. How many boxes are completely full, and how many vials are left over? Then: how many boxes must she carry to take every vial?
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Answer:
Did you know? Most vaccines must stay cold the whole way from the factory to the arm. That chain of fridges has a name: the cold chain.
3.
A nurse sets out 6 trays with 24 doses on each. By the end of the day she has used 89 doses. How many are left?
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Answer:
Did you know? Smallpox is the only human disease ever wiped out completely, and vaccines are how it was done.
4.
One cool box is 5/8 full. Another is 2/3 full. Which box holds more? How do you know?
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Answer:
Did you know? The word vaccine comes from vacca, the Latin for cow — the first one was made from a mild cattle disease.
5.
A rectangular fridge shelf has a perimeter of 46 cm. One side measures 14 cm. How long is the other side? What is the area of the shelf?
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Answer:
Did you know? When enough people in a town are vaccinated, a germ runs out of people to jump to. That protects the few who cannot be.
1. GUIDED
A cool box is filled in two goes. In the morning 1/6 of it is filled. In the afternoon another 3/4 is filled. How full is the box now?
A common bottom number for 6 and 4 is
1/6 = /12 and 3/4 = /12
Now add the top numbers only, keep the bottom:
Answer:
Did you know? Some vaccines need a second dose weeks later. The first teaches, the second makes the lesson stick for years.
2.
A store of vaccine is 5/6 full. Over one week, 3/8 of the store is used. How much is left?
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Answer:
Did you know? Antibodies are shaped to lock onto one germ and no other, a bit like a key cut for a single door.
3.
A clinic orders 36 cartons, and each carton holds 45 doses. How many doses is that altogether?
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Answer:
Did you know? A sore arm after a jab is not the vaccine hurting you. It is your own defence arriving at the spot.
4.
A vial holds 12.5 mL. A nurse draws 3.6 mL, then later 4.25 mL. How much has she drawn, and how much is still in the vial?
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Answer:
Did you know? Your body keeps memory cells for decades. Some people still carry a defence from a jab given in childhood.
5.
A team vaccinates 1,824 people in 6 days, at a steady rate. At that same rate, how many would they vaccinate in 11 days? Those records are filed into folders of 9 — how many complete folders is that, and how many records are left over?
SHOW YOUR THINKING
Answer:
Did you know? Polio has been pushed out of almost every country on earth by vaccination campaigns that went village by village.
3rd Grade
1. 800 doses.
128 × 7 = 896 handed out over the week, then 896 − 96 = 800 actually used. Multiply first, subtract second.
2. 9 full boxes, 3 left over — but 10 boxes to carry them all.
75 ÷ 8 = 9 remainder 3. Those 3 spare vials still have to travel, so one more box: 10.
3. 55 doses left.
6 × 24 = 144 set out, then 144 − 89 = 55.
4. The 2/3 box.
Twenty-fourths: 5/8 = 15/24 and 2/3 = 16/24. So 2/3 holds more, by one twenty-fourth — and note it is the fraction with the smaller numbers this time.
5. Other side 9 cm; area 126 square cm.
Halve first: 46 ÷ 2 = 23, one long side plus one short. Then 23 − 14 = 9 cm. Area = 14 × 9 = 126 square cm.
4th Grade
1. 11/12 of the box.
Twelfths: 1/6 = 2/12 and 3/4 = 9/12, so 2/12 + 9/12 = 11/12. Add the tops, keep the bottom. Both had to change here — neither bottom was already 12.
2. 11/24 of the store.
Twenty-fourths: 5/6 = 20/24 and 3/8 = 9/24. 20/24 − 9/24 = 11/24. The bottom number never changes once you have it.
3. 1,620 doses.
36 × 45. Split it: (36 × 40) + (36 × 5) = 1,440 + 180 = 1,620.
4. 7.85 mL drawn; 4.65 mL left.
Pad and line up the points. 3.60 + 4.25 = 7.85. Then 12.50 − 7.85 = 4.65 mL. Padding matters most in the subtraction: 12.5 read as 12.05 gives 4.20.
5. 3,344 people — 371 complete folders, 5 left over.
Find one day first: 1,824 ÷ 6 = 304 a day. Then 304 × 11 = 3,344. Finally 3,344 ÷ 9 = 371 remainder 5. Check: 3,339 + 5 = 3,344. ✓