using System;

using System.Linq;

using System.Linq.Expressions;

public class Program

{

    public static void Main()

    {

        var values = new[] { 3, 1, 2 };

        Console.WriteLine("Highest: " + values.AsQueryable().Order(x => x, true).First());

        Console.WriteLine("Lowest: " + values.AsQueryable().Order(x => x).First());

    }

}

​

public static class Extensions

{

    public static IOrderedQueryable<TSource> Order<TSource, TKey>(

        this IQueryable<TSource> source, 

        Expression<Func<TSource, TKey>> keySelector, 

        bool descending = false)

    {

        return descending ? source.OrderByDescending(keySelector) : source.OrderBy(keySelector);

    }   

}