Physical Science
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2nd Grade Science › Physical Science
Which of these photos demonstrates a change from heating or cooling that cannot be reversed?
Explanation
The photo that demonstrates a change that cannot be reversed is the pan of brownies. Writing with markers can be erased and reversed, ice cubes can be heated and cooled multiple times between states, and a puzzle can be taken apart and put back together. Once the ingredients are mixed into a batter and then heated, the brownies cannot be turned into mixture again.
Observable properties classify all of the items listed. What observable property are all of the items in "Category 2" sorted by?
Shape
Hardness
Color
Texture
Explanation
Observable properties are characteristics of an object or material that can be gathered using the five senses. When looking through each category, there is a common property that groups the items. In "Category 2," all of the items are round, so they are classified by shape.
Bella put a dirty sock in a box. She described it to her sister using observable properties, and her sister had to guess what it is. Which set of features matches the sock?
Round, red, hard, and smooth
Irregular shape, soft, white, and smelly
Square, hard, green, and bouncy
Irregular shape, hard, rough, and smelled fruity
Explanation
An observable property is something that describes an item or material and is gathered using the five senses. A dirty sock is an irregular shape, soft, white, and smelly. Someone could touch, smell, and see a dirty sock and find all of these properties are true.
Blair and her class build two bridges as a competition. The goal was to get the most cars across before the bridge collapsed. They have to choose the best design to improve on and send to the science fair.
Based on the data table, which bridge should they select and why?
Bridge A; it looked the coolest out of the two bridges and the class got to eat popsicles to make it
Bridge A; it held the most cars, wobbled but did not fall
Bridge B; it held three cars before it fell and that is pretty good
Bridge B; the class got to chew gum to make this bridge so they should pick it
Explanation
When building a bridge in real-life, there is a massive amount of planning and testing done to ensure it is safe and sturdy. This class had good plans and materials for building both bridges, but "Bridge A" seems like the most reliable choice for the science fair entry. It was able to hold up six toy cars and did not fall. It did wobble some so the class can make improvements on that portion of the bridge. "Bridge B" collapsed after the weight of three toy cars, so it doesn't seem like the most sturdy bridge.
Grace wants to see which object she should NOT choose to clean up a spill. Based on the absorbency (ability to soak up something) property of each item, which item would be the worst to select?
Item 1
Item 2
Item 3
There is no way to tell which item she should not use.
Explanation
Different materials have specific purposes and are best suited for certain tasks. In this case, "Item 1" is not absorbent at all, and Grace is trying to clean up a spill. This item would NOT be the best choice to clean up a liquid. If Grace wants to clean it up quickly, "Item 3" would be her best choice instead!
Jessa mixed sand and paperclips. She wants to remove the paperclips without touching them. Her teacher gives her the choice of three different tools to use. Which tool is best suited for removing paperclips without touching them?
Tweezers
Bar Magnet
Sifter
None of these tools would work
Explanation
Different materials have specific purposes and are best suited for certain tasks. Jessa has to remove small, metal paperclips without touching them. The size and color of the tool do not matter in this case, and they do not affect Jessa's decision. The bar magnet is magnetic, so it should pick up the paperclip when it is moved close to it. Magnets do not need to touch other objects to affect them if they have magnetic qualities. This would be the tool most suited to her task.
I melted a crayon and then put the crayon in the refrigerator, and it did not form back into the crayon shape, just a hard pile of colored wax. I did this multiple times, and it always happened the same way. I think heating can be reversed. This is an argument based on evidence.
True
False
Explanation
This argument is based on evidence. There is no personal opinion or thoughts involved in the statement. The popsicle investigation provides data to make conclusions from, so it is evidence-based and supported.
Which statement is based on opinion instead of evidence?
Artists love to make mosaic pieces of artwork.
Mosaic pieces of artwork are examples of breaking up larger pieces and putting them together to make something new.
Pieces of mosaic artwork are made of tile, glass, ceramic, and other pieces of material.
Mosaic art pieces can come in multiple colors, patterns, and designs.
Explanation
Personal opinion statements will include thoughts and feelings from the author. "Artists love to make mosaic pieces of artwork." is a statement that provides for individual ideas and makes a sweeping statement that "artists love to make mosaics." This is not something that can be proved scientifically and is just one person's opinion.
Becky says some changes caused by heating cannot be reversed. Maddy says all changes can be reversed. Their mother cooked hashbrowns for breakfast. Using this example, which sister is correct, Becky or Maddy, and why?
Becky; once the potato has been cooked there is no way to reverse it back into the form it was before
Maddy; the potato can be uncooked and put back into its original form
Neither; neither Becky nor her sister Maddy is correct
There is not enough information to tell who is correct or incorrect
Explanation
Some changes caused by heating or cooling cannot be reversed. This statement is true, so in the cases of Becky and her sister Maddy, Becky is correct. Some changes caused by heating, like cooking a potato, can't be reversed. There is no way to take the potato from cooked and get it back into its raw form.
Which photo represents whole objects being broken down into smaller pieces to make something new?
Explanation
The photo that represents an object being broken down into smaller pieces to make something new is the pizza. The individual ingredients are added to make the entire pizza. Olives are cut up, tomatoes crushed, peppers cut, etc. to be added onto the crust and baked. This is an example of something new being created from the smaller pieces of objects being broken up.