The Higgs Boson  (I took most of this from an answer submitted by a student .... with some minor clarifications)

In 2012,  physicists were elated to have found "the God particle" known as the Higgs Boson.

Part 1 - How was this particle discovered?  Give a brief overview of the "tool" used to discover this particle.

The Higgs Boson particle was discovered using the Large Hadron Collider which is essentially a huge particle accelerator.  Using super chilled electromagnets to create the rapid movement of charged particles, physicists watch these particles collide then wait and see what happens.   Theory predicted that the Higgs Boson can be isolated as the colliding particles decay into other sub-particles. 

Part 2 - What is the function of the Higgs Boson?  That is, what does it do?

The Higgs Boson is believed to be the particle which gives all matter its mass.  The theory of Higgs Boson is that there is a high energy field that exists everywhere in the universe.  Particles travel through this energy field and attract and connect with Higgs Boson particles, which then cluster around them to form mass.  Here is an analogy that might make sense to you.  Suppose Joe Blow and Beyoncé walk into a Hollywood party.  Joe Blow is able to move freely throughout the room because he is a nobody.  Not the case with Beyoncé!  Everyone is attracted to her and she has great difficulty moving around the room.  In physics we would associate Joe Blow as having a low mass and Beyoncé as having a high mass because mass is a measure of inertia.

Part 3 - Why was the discovery of this particle important?

The standard model (which has been around for many years) does a good job of explaining the existence and interactions of subatomic particles but could not account for their mass.  This discovery can be thought of as an "add-on" which gives physicists a better understanding of the universe.  If the Higgs Boson had not been discovered, it might have forced physicists to scrap everything and start over.

Part 4 - There are several other studies in the world of particle physics that have enormous consequences for astronomers.  One of them is to explain why there is so much more matter in our universe than antimatter.  That is, why aren't both found in equal quantity?  What is the status of this investigation?  Has a solution been found?

The question of why there is more matter than antimatter has plagued scientists.  It does not coincide with current theories of how mass and energy react to each other and is therefore very unsettling to many scientists.  The Standard Model of particles states that as matter and antimatter collide, they destroy one another.   If created in equal amounts, any matter in this universe would be destroyed by antimatter ... leaving us with a universe filled with nothing but radiation.  Why, then, is there so much more matter than antimatter? 

Scientists are trying desperately to resolve this inconsistency to hold the Standard Model intact.  The key may be found in particle accelerators when they observed mutations in particles known as strange B meson decays.  One of the experiments has observed strange B mesons ‘flipping’ between matter and antimatter.  However, the rate at which they flip in one direction is slightly faster in one direction than the reverse direction (known as a CP violation).   This, in itself, has not completely solved the problem but if similar CP violations are observed (in the Higgs Boson, for example), it could eventually explain why we live in a universe dominated by matter (rather than antimatter).

There is another new idea (2019) that may solve the lack of antimatter we see in our universe.  Imagine that there is not just one, but three different types of Higgs Bosons (and we only found one of those types).  I won't pretend to understand the details of this hypothesis but the central idea is that all three proposed Higgs particles would have been effective at destroying antimatter at a very, very, vary early time just after the Big Bang.  Read more about the Higgs Troika Theory.