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This part is on Weight and Balance with Rocks
By – Scott Dan
Subject – Science, Math
Grade Level – 1st – 2nd
Concept: Weight and Balance
A variety of rocks in composition and size (must include pumice), balances, handout for comparing the rocks, 12 containers for the rocks, a variety of colored dot stickers (at least 5 colors) and a felt tip pen.
Have the children place the rocks that they have collected into pans (each group of two combining their rocks). If the children do not have a large enough variety, place a few extra rocks into the container. Make sure that every group has a least one lava rock (pumice). Label the rocks by placing a colored dot onto the first five rocks. For the next five rocks, place a dot on the middle of each sticker. For every group of five rocks, add an additional dot.
1. Ask the children to join you at the calendar center. Show them a balance and ask them if they know what it is and what it does. Ask them what they could use it for along with their rocks that they have collected.
2. Show the children two rocks and ask them to guess which one is heavier. Place the two rocks onto the balance and ask them which one is heavier. Ask them to explain their answer (how do they know that rock A is heavier than rock B).
3. Ask them if the size of the rock helped them decide which one is heavier. Ask them if they believe that the larger rock will always be the heaviest. Also ask them about color and shape. Finally, ask them if there are any other observations that will help them know if a rock is heavier than another rock.
4. Ask the children to go back to their desks with their partner (they already know who their partner is because they combined their rocks into one container earlier in the day). Ask them to take out their container of rocks while you pass out balances and a data sheet to each group of children.
5. Explain the data sheet with the children by doing a couple of examples with them. The children are to take two rocks out and record them onto their paper. They will do this by using their crayons and using the colored dot that is on their rock. The children may either right the answers in the spaces provided, or the may draw them. Finally, the children will be asked which one is heavier. They are to record the rock that is heaviest by recording the colored dot that is on the rock. Ask the children to also pay attention to the rocks color and shape. Tell them you will want to know if these two characteristics have anything to do with the rocks weight. They may write in the colors and shapes of the rocks in each space if they want.
6. Ask the children to continue on their own until they have completed 10 comparisons (2 sheets).
7. As the children finish, give them a spinner marked more or less. Have one person in each group use the spinner and pick out a rock. The other child is to pick out another rock that either weighs more or less, depending on what the spinner read.
8. Once all the groups are done with their data sheets and have had a chance to play the game, ask the class some questions.
A. What did you find when you filled out your data sheets?
B. Did the larger rock always weigh more?
C. Did one color weigh more than another? Shape?
D. Is there anything interesting that you want to share?
E. Ask them which rock was the heaviest in their collection? The lightest? They may need extra time to figure this out.
F. Ask the children why they believe one rock is heavier than another.
G. Is there anything that we can do to find out this answer?
9. Use the children’s suggestions to test their beliefs. Many children may suggest that the weight of any particular rock is due to its make-up (that is, what parts go into making up the rock). Children may suggest cracking open a couple of rocks to compare the inside, looking at them really close with a magnifying glass, looking them up in books or asking a scientist (geologist).
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