Counting of the Omer
During the seven weeks from Passover to Shavuot (Pentecost) , Jewish people would do what is called the counting of the omer. Which was used for helping them to determine when it was exactly 50 days after Passover. An omer is a measure of grain, which was brought into the temple on the second day of Passover as an offering. Then it was to be counted for seven weeks. On the 50th day, they would bring in the offering of the first fruit into the temple. They would use the grain as a way of measuring the seven weeks until Shavuot. For them it was a joyous time because they were looking forward to what was up and coming. Think of this in the same manner as a child does before their birthday.