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
A possessive shows that something belongs to someone. Choose the correct form in each sentence. Then explain how you decided whether the apostrophe goes before or after the s.
- Our (dog’s / dogs’) water bowl is empty. (We have one dog.)
- All five (teacher’s / teachers’) cars were in the parking lot.
- The (children’s / childrens’) paintings hung in the hallway.
- Both (girl’s / girls’) jackets were left on the bus.
- The (team’s / teams’) coach called a timeout. (There is one team.)
Answer and teacher notes
1. dog’s 2. teachers’ 3. children’s 4. girls’ 5. team’s
Two-step method: first write the owner word correctly (singular or plural), then add the possessive. If the owner word does not end in s, add ‘s (dog → dog’s, children → children’s). If it is a plural that already ends in s, add just the apostrophe (teachers → teachers’, girls → girls’). Sentence 3 is the trap: children is already plural, so childrens’ is never correct. Common mistake: adding an apostrophe to a plain plural that owns nothing, as in “The dog’s are barking.”
Math
A shipping box is a rectangular prism that is 12 inches long, 10 inches wide, and 8 inches tall.
- What is the volume of the box?
- How much cardboard covers the outside of the box (its surface area)?
- How many 2-inch cubes could you pack inside with no gaps?
- A classmate says a box with every side twice as long would hold twice as much. Is that right?
Answer and teacher notes
1. V = 12 × 10 × 8 = 960 cubic inches.
2. Three pairs of matching faces: 12 × 10 = 120, 12 × 8 = 96, 10 × 8 = 80. SA = 2 × (120 + 96 + 80) = 2 × 296 = 592 square inches.
3. Along each edge: 12 ÷ 2 = 6, 10 ÷ 2 = 5, 8 ÷ 2 = 4. 6 × 5 × 4 = 120 cubes. Check: each cube is 2 × 2 × 2 = 8 cubic inches, and 120 × 8 = 960. ✓
4. No. A 24 × 20 × 16 box has volume 7,680 cubic inches, which is 7,680 ÷ 960 = 8 times as much, because all three dimensions doubled (2 × 2 × 2 = 8).
Common mistake: mixing up volume (cubic inches, space inside) and surface area (square inches, material outside). Extension: how many times more cardboard would the doubled box need? (2 × 2 = 4 times, since area uses only two dimensions.)
Science
Rub a balloon on your hair or a wool sweater, then hold it against a wall. It sticks! (a) Rubbing moves tiny charged particles called electrons onto the balloon. Electrons have a negative charge. What charge does the balloon have now? (b) Nobody rubbed the wall. Why is the wall still attracted to the balloon? (c) After a while, the balloon falls. What do you think happened to its charge?
Answer and teacher notes
(a) The balloon gains extra electrons, so it becomes negatively charged. The hair or sweater loses electrons and is left with a positive charge. (b) The balloon’s negative charge pushes the negative charges in the wall’s surface a little bit away, which leaves the spot nearest the balloon slightly positive. Opposite charges attract, so the balloon clings to that spot. (c) The extra electrons slowly leak off the balloon onto the wall and into the air, so the charge fades and gravity wins.
The demo can fail depending on the wall material and how humid the air is, which is worth testing as a class. Connection: the first photocopy was made on October 22, 1938, 88 years ago today. Photocopiers use static charge to make powder stick only where the dark parts of the image are. Follow-up: why do you get more shocks from doorknobs in dry winter weather?
Sources: Science World: Can you stick a balloon to the wall without glue or tape?; The Henry Ford: Light and Static: The Origins of the Xerox Copy
Social Studies
Texas declared independence from Mexico on March 2, 1836. On October 22, 1836, Sam Houston was inaugurated as the first elected president of the Republic of Texas in the town of Columbia, the republic’s first capital. The temporary president had picked Columbia partly because it had housing for lawmakers and a newspaper. Texas stayed an independent republic until December 29, 1845, when it became the 28th U.S. state. (a) How many years ago was Houston’s inauguration? (b) About how many years was Texas an independent republic? (c) Why would housing and a newspaper matter so much to a brand-new government?
Answer and teacher notes
(a) 2026 − 1836 = 190 years, so today is the 190th anniversary. (b) From March 1836 to December 1845 is almost 10 years (about 9 years and 10 months). Accept “about 9 years” if students subtract 1845 − 1836.
(c) Answers will vary. Lawmakers traveled from far away and needed somewhere to stay while they met. A newspaper let the government share new laws and news with people across Texas, at a time with no radio, phones, or internet. The first Congress, meeting in Columbia, set up an army and navy, a post office, a land office, courts, and a national seal and flag. Columbia did not stay the capital for long: the executive office moved to the new town of Houston in April 1837. Map tip: Columbia (today West Columbia) is near the Gulf Coast, southwest of Houston.
Sources: Texas Historical Commission: Columbia (First Capital of Texas); Texas State Library and Archives: Annexation Timeline
Current Events
Scientists reported this week that they discovered a new kind of freshwater snail, Erhaia dijiang, in a limestone cave in Yunnan, China. The snail has no eyes, a nearly see-through shell, and a body with no color. The cave is 2,062 meters above sea level, the highest any cave snail in its family has been recorded. The snails hide under rocks when a light shines on them. In a field survey, researchers found only three living adults and one empty shell, and no young snails. (a) Convert 2,062 meters to feet (1 meter ≈ 3.28 feet). (b) Why might an animal that lives its whole life in a dark cave not need eyes or colorful skin? (c) Why are scientists worried that they found no young snails?
Answer and teacher notes
(a) 2,062 × 3.28 ≈ 6,763 feet, well over a mile high. (Using 3.28084 gives about 6,765 feet.)
(b) Answers will vary. In total darkness, eyes can’t help an animal see, and color can’t help it hide or attract a mate, so these traits give little advantage. Many cave animals lose eyes and color over many generations. Push for careful wording: the snail didn’t “decide” to lose its eyes; the change happens slowly through evolution. (c) Without young snails, the group may not be replacing itself, and with only a few adults, one flood or change to the cave could wipe it out. The authors call the snail’s future “far from optimistic” and are asking for protection of its habitat. It is also the first freshwater cave snail documented in China. The study appears in Subterranean Biology.
Source: ScienceDaily: Scientists Discover Ghostly, Eyeless Creature Hidden in Chinese Cave (Pensoft Publishers)
Keep going
More bell ringers: Bell ringers for middle school · Math bell ringers · Science bell ringers · Social studies bell ringers · Grammar bell ringers · 100 bell ringer questions
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