Demonstrate estimation by rounding, or changing numbers to other numbers that are easier to work with. For example, 1,283 plus 4,987 would be estimated as 1,000 plus 5,000, which equals 6,000.
Take a trip to the grocery store or peruse advertisements for comparison shopping. Ask students to figure out the best deal on apple juice, for example, by comparing the price in relation to the quantity in the container.
Look for discounted items in the ads. Ask students to estimate the actual price they will pay after the discount. Rather than trying to figure out 25 percent off $39.97, round the original price to $40. Then it is easy to see you will save about $10 on the purchase and pay about $30.
Set up a restaurant role play and have students order from a menu and get the bill from the pretend waiter. Students can estimate what 15 to 20 percent of the bill would be by rounding the total to the nearest dollar and working out the percentage from the whole number.
Ask students to choose a destination and plan a road trip. Teach them to use a map scale to calculate the distance. Instead of trying to figure out what fraction of the distance is in 1/16 of an inch, tell them it is OK to round the distance to the nearest whole or half inch for estimation purposes. Have them estimate the distances from the starting point to each city or stopover point.