Down and strange quarks have the same charge but different masses, with strange being like an older sibling to down. There are three generations of quarks: up and down, charm and strange, and top and bottom. This same pattern is seen in leptons, which are the second type of fundamental particle. Hadrons are particles made of quarks. The most common hadrons are protons and neutrons, which are made of up and down quarks. Students are asked to determine that a proton contains two up quarks and one down quark to give it a net charge of +1, while the neutron contains two down quarks and one up quark to give it a net charge of 0.

1. Slide 1:Title.Intoroduce the session,andyourselfif necessary.
Slide 2:Quarks. Explainthe conceptof quarksas the smallestthingwe have found.The conceptof
fundamental particlesasindivisible.Matterandantimatter.Askwhattheynotice aboutdownand
strange (theyhave the same charge – explainthatitismass thatmakesthemdifferent).

2. Slide 3:Generations.
Downand strange have the same charge but differentmasses –strange islike anoldersiblingof down.
Discussthe otherthree quarks(charm,bottomand top) – these are not normallyexaminable,butthey
followthe same patternasup anddown:we have three generations.Thispatternisrepeatedinthe
leptonfamily.Discussleptonsasthe secondtype of fundamental particle.

3. Slide 4:Particle Types.Explainthata hadronisa particle made outof quarks.Quarks don’tlike tobe on
theirown(we will findoutwhylater),sotendtosticktogether.The mostcommonhadronsare protons
and neutrons,made of upand downquarks.Askthe studentstotry to work outhow to make a proton,
whichhas a charge of +1. If necessary,give themthe hintthatthere are three quarksina proton.(They
needtowork outthe combinationof three chargeswhichaddsto1). Do the same for neutrons,once
theyhave workedthisout