All week long, Jim Cramer has been sharing with investors some key market indicators that can signal stocks want to trade higher. Cramer spoke to the students of Ohio State University's Fisher College of Business on Wednesday, and he told them that one of the most important indicators for the market's overall health is breadth.Breadth is simply a measure of the number of stocks trading up vs. trading down. When the market is drifting lower and the number of stocks going up outnumbers those going down, it often means the market is much healthier than it seems. Cramer has also picked out three key market "tells" that can give investors an early clue that the market wants to trade higher. One of those tells is leading technology stock Apple ( AAPL). Cramer explained that if Apple starts to trade higher during a market selloff, then the market will soon follow. Thanks to Cramer's experience trading as a hedge fund manager he can spot what's happening below the surface on Wall Street. Once Cramer dissects what's going on, he shares that information with investors. Investors can then use that info to get an edge on the market before they put capital to work. Recently, Cramer found opportunity in early-cycle stocks, stocks to scoop up when the market pulls back and tech stocks. Here are some Cramer highlights from over the past week as aggregated from his "Mad Money" TV show, the "Stop Trading!" segment on CNBC and his RealMoney blog posts (these blog post require a RealMoney subscription). To read more, visit Stockpickr.com.