NewFree with an accountClass 7TechnologyBeginnerLab bench
Binary numbers: how a computer counts with bulbs
A computer stores numbers as bits that are either on (1) or off (0); each bit is worth twice the one to its right, and the number is the sum of the bits that are on
Four bulbs are worth 8, 4, 2 and 1. Switch them on and off to make numbers, and find out how a computer stores every number with just ones and zeros.
A password is safer when it is long and mixes letters, digits and symbols, because the number of possible passwords to try grows enormously
A computer tries a million passwords every second. Make a password longer, add letters and symbols, and see how long it would take the computer to try them all.
NewFree with an accountClass 8TechnologyBeginnerLab bench
How an ATM gives you money
An ATM is a digital system: it takes inputs (card, PIN, amount), checks them against the bank's computer, and only then gives outputs (cash, a new balance)
Put in a card, type a PIN and ask for cash. Watch the ATM check the PIN, the money in the account and the daily limit, then count out Rs 1000 and Rs 500 notes.