If 8 December 2007 was a Saturday, what day of the week was 8 December 2006?

Introduction / Context:
This question asks you to move one year backward from a known date. You are told the weekday for 8 December 2007 and must determine the weekday for 8 December 2006. Such questions train you to handle year to year shifts using the concepts of leap years and odd days.

Given Data / Assumptions:

• 8 December 2007 was a Saturday.
• We must find the weekday on 8 December 2006.
• 2007 is a normal year with 365 days.
• The dates are exactly one year apart.

Concept / Approach:
The key idea is that a normal year has 365 days, which gives 1 odd day, while a leap year has 366 days, giving 2 odd days. If we move forward by one normal year, the weekday advances by one day. If we move backward by one normal year, the weekday moves back by one day. Here we are moving backward by one normal year.

Step-by-Step Solution:
Step 1: Note that 2007 is a non leap year, so it has 365 days. Step 2: Exactly one year separates 8 December 2006 and 8 December 2007. Step 3: One normal year corresponds to 1 odd day. Step 4: When we move from 8 December 2006 to 8 December 2007, the weekday increases by one day. Step 5: We know that 8 December 2007 is a Saturday, so if we move backward one day we get the weekday for 8 December 2006. Step 6: The day before Saturday is Friday, so 8 December 2006 was a Friday.

Verification / Alternative check:
You can verify by moving forward from 2006 to 2007 instead. If 8 December 2006 was Friday, then adding one day for the single odd day of the normal year 2007 gives Saturday for 8 December 2007, which matches the given information. This confirms that our logic is consistent.

Why Other Options Are Wrong:
Sunday: This is one day after Saturday and would correspond to moving forward instead of backward.
Thursday: This is two days behind Saturday, which would require two odd days, not one.
Tuesday: This is even further away and does not fit any simple one year shift scenario for a normal year.

Common Pitfalls:
Students sometimes forget whether to move forward or backward when going from a given year to an earlier year. Another mistake is to assume that every year changes the weekday by two days, which is only true for leap years. Always check whether the intervening year is leap or normal and move the weekday accordingly.

Final Answer:
Hence, the day of the week on 8 December 2006 was Friday.