Question

using only these supplies, which question can elena investigate with an experiment? do small rocks or large rocks skip more times when thrown across the river? do rocks skip more times when thrown across a river or across a pond? do round rocks or flat rocks skip more times when thrown across the river?

Explanation:

To determine which question Elena can investigate with an experiment, we analyze each option:

1. For "Do small rocks or large rocks skip more times when thrown across the river?":

• The independent variable (rock size) can be controlled (using small vs. large rocks), and the dependent variable (number of skips) can be measured, all within the same river (constant environment).

1. For "Do rocks skip more times when thrown across a river or across a pond?":

• The environment (river vs. pond) changes, which introduces multiple variables (e.g., water depth, current, surface area) that are hard to control, making it less feasible as a simple experiment with the given supplies.

1. For "Do round rocks or flat rocks skip more times when thrown across the river?":

• While rock shape is a variable, the problem states "using only these supplies"—but we don’t know if Elena has both round and flat rocks available. However, the first option (small vs. large rocks) is more straightforward to test with typical supplies (easier to find small/large rocks than strictly round/flat ones) and a constant environment.

Answer:

Do small rocks or large rocks skip more times when thrown across the river?