Every lesson, ready to teach.

What are the smallest pieces of matter, how do we know they exist, and how do scientists keep track of the different kinds?

How can fewer than a hundred kinds of atoms build millions of different substances, and how do scientists model the ways atoms join?

How can you tell one substance from another when they look the same, and which measurements can be trusted to do it?

Where do producers get the matter and the energy they use to build their bodies, and how does that supply reach every other living thing?

How do living things get usable energy and building materials out of food, and where does the matter go?

How do matter and energy move through an ecosystem, and why does matter come back around while energy does not?

How does the same matter keep moving through Earth's living and nonliving parts, and what happens to the cycles when people change them?

How can rock layers tell us the order of events in Earth's past, and when can they tell us how long ago those events happened?

How do scientists use rocks, fossils and dated materials to reconstruct and organize a history that no one was there to see?

How does energy flowing from the Sun and from Earth's interior set rock, water, air and living things in motion?

How does Earth's surface change through time, and how do scientists compare changes that are tiny or enormous, instant or almost endless?

What evidence is enough to say that a new substance formed, and what evidence only looks like it?

What happens to atoms during a chemical reaction, and why does the mass of a sealed system never change?

How does energy move between a chemical reaction and its surroundings, and how can engineers control that flow to build a useful device?

Where do synthetic materials come from, why do people choose them over natural ones, and what do those choices cost?

What evidence convinced scientists that the continents move, and how did that evidence turn a hypothesis into the theory of plate tectonics?

How does the rock cycle model the ways Earth's materials move and change, and where does the energy for each change come from?

What moves Earth's water from place to place, what makes it change between solid, liquid and gas, and why can the same water end up in so many different places?

Why are mineral, energy and groundwater resources concentrated in some places and missing from others, and what happens to that pattern as people use them?

What do living things need from their surroundings, and what happens to organisms and populations when a needed resource runs short?

Why do the same kinds of relationships between species appear in ecosystems that share no species at all, and how can knowing those patterns let us predict what happens when one population changes?

How do ecosystems change over time, and how can we use evidence to argue that a change to one part of an ecosystem affects the populations living there?

How does the motion of particles explain what a solid, a liquid and a gas can do, and what happens to that motion when thermal energy is added or removed?

When thermal energy is added to or removed from a substance, what happens to how its particles move, to its temperature and to its state?

How can people forecast and prepare for volcanic eruptions and earthquakes when only one of them usually gives warning signs?

How do scientists use patterns in data to forecast where and when mass wasting, tsunamis and floods are likely, and how do those forecasts shape the technologies and plans people use to reduce the harm?

Why does biodiversity matter to how ecosystems work and to people, and how can we judge which plan best protects it?

What do healthy ecosystems do for people, and how should a community decide whether to protect an ecosystem or pay to replace the services it provides?

How do a growing human population and rising use per person change ecosystems, and how can people design, test and choose solutions that protect biodiversity and the services ecosystems provide?