Five warm-ups for grades 6–8. Each takes three to five minutes. Answers and teacher notes are in the collapsed box under each prompt.
ELA
Homophones sound the same but have different spellings and meanings. Fill in each blank with the correct word. Then write one sentence of your own that uses their, there, and they’re correctly.
- The team left ____ jerseys in the locker room. (their / there / they’re)
- ____ going to the science fair after lunch. (Their / There / They’re)
- The dog wagged ____ tail. (its / it’s)
- ____ going to rain this afternoon, so bring a jacket. (Its / It’s)
- Is that ____ backpack, or is it mine? (your / you’re)
Answer and teacher notes
1. their 2. They’re 3. its 4. It’s 5. your
The apostrophe test: if you can swap in the two full words, use the contraction. They’re = they are, it’s = it is (or it has), you’re = you are. If the swap sounds wrong (“The dog wagged it is tail”), use the word without an apostrophe. Memory tip: there contains the word here, and both name a place. Common mistake: writing it’s for ownership. Possessive pronouns (his, hers, its, yours, theirs) never take an apostrophe.
Math
A fall jacket costs $80. This week it is 25% off, and then an 8% sales tax is added to the sale price.
- What is the sale price before tax?
- What is the final price with tax?
- A friend says, “25% off and 8% tax is the same as 17% off, so it costs $66.40.” Is your friend right? Explain.
Answer and teacher notes
1. Discount: 25% of $80 = 0.25 × 80 = $20. Sale price = $80 − $20 = $60.00.
2. Tax: 8% of $60 = 0.08 × 60 = $4.80. Final price = $60 + $4.80 = $64.80.
3. No. The 8% tax is taken from the smaller sale price ($60), not the original $80, so you can’t just subtract the percents. One-step check: 80 × 0.75 × 1.08 = 80 × 0.81 = $64.80. You pay 81% of the original price, which is the same as 19% off, not 17% off.
Extension: does it matter whether the store takes the discount first or adds the tax first? Have students try it (80 × 1.08 = 86.40, then 86.40 × 0.75 = $64.80). Multiplication can be done in either order, so the final price is the same.
Science
In summer, most tree leaves look green. In fall, many turn yellow, orange, or red. Scientists say the yellow and orange colors were already in the leaves all summer. (a) If the yellow was there all along, why couldn’t we see it? (b) What changes in the fall, as the days get shorter and cooler, that lets the yellow show? (c) Red colors work differently. Based on your answer to (a), what might be different about red?
Answer and teacher notes
(a) Leaves are full of chlorophyll, the green pigment plants use for photosynthesis. There is so much of it that it hides the yellow and orange pigments, called carotenoids.
(b) All summer, trees keep replacing chlorophyll as it breaks down. Cooler temperatures and less daylight slow photosynthesis, so the tree stops replacing it. As the green fades, the carotenoids that were there all along show through. A first frost speeds up the breakdown of chlorophyll. (c) Red and purple come from anthocyanins, which are mostly made new in late summer and fall rather than uncovered. They are especially common in trees such as red and sugar maples. Follow-up: why might the same kind of tree look brighter red in some years than others?
Source: USDA: The Biology of Fall Leaves: It’s All About Chemistry
Social Studies
On October 19, 1781, British General Charles Cornwallis surrendered his army at Yorktown, Virginia, to American and French forces led by George Washington. A French fleet of 24 ships under Admiral de Grasse controlled the waters nearby, and about 14,000 French and American soldiers surrounded the town on land. (a) How many years ago was the surrender? (b) Cornwallis’s army was trapped on a peninsula next to the water. Why did it matter so much that the French fleet controlled the sea? (c) What does this tell you about why the Americans wanted allies during the Revolution?
Answer and teacher notes
(a) 2026 − 1781 = 245 years.
(b) With soldiers on land and French ships on the water, the British could not escape by sea or get supplies and reinforcements from British ships. They were surrounded on every side. On September 5, 1781, a British fleet tried and failed to defeat de Grasse at the Battle of the Virginia Capes. (c) Answers will vary. The Americans did not have a strong navy, and France supplied ships, soldiers (about 4,000 troops under the comte de Rochambeau marched south with Washington), and money. About 8,000 British soldiers became prisoners, and the surrender made American independence nearly certain. Map tip: show Yorktown between the York and James Rivers near Chesapeake Bay.
Source: Britannica: Siege of Yorktown
Current Events
Today, Monday, October 19, Japan’s space agency, JAXA, is scheduled to launch the MMX (Martian Moons eXploration) spacecraft at 3:41 p.m. Eastern time. It will study Mars’ two small moons, Phobos and Deimos, and try to bring a sample of Phobos back to Earth in 2031. It carries a small rover named Idefix with a mass of 25 kilograms. Gravity on Phobos is so weak that the rover would weigh about as much as 15 grams does on Earth. (a) 25 kilograms = 25,000 grams. About how many times lighter will the rover feel on Phobos? (b) Why would a rover have to drive extra carefully where gravity is that weak? (c) What time is the launch in Central time?
Answer and teacher notes
(a) 25,000 ÷ 15 ≈ 1,667 times lighter. Check: 15 × 1,667 ≈ 25,005, close to 25,000.
(b) Answers will vary. With almost no weight pressing it down, a rover’s wheels get very little grip, and a bump or a fast turn could bounce it off the ground or tip it over. (c) Central time is one hour behind Eastern, so 2:41 p.m. CDT. The plan: reach Mars in August 2027, collect at least 10 grams of Phobos material, and return it to Earth in 2031. NASA contributed an instrument that will measure what Phobos is made of, plus a test version of a gas-powered sampler. Scientists hope the sample will show whether Phobos and Deimos are captured asteroids or pieces thrown off Mars by a giant impact. Note: launch dates can slip because of weather or technical checks, so confirm the launch happened before class.
Sources: ESA: Mars moon lander set to launch on 19 October; NASA: NASA to Help Unlock Mysteries of Mars’ Moons in Upcoming Mission
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