TSC Ratings provides exclusive stock, ETF and mutual fund ratings and commentary based on award-winning, proprietary tools. Its "safety first" approach to investing aims to reduce risk while seeking solid outperformance on a total return basis.If the stock market is a bellwether for the economy, expect a revival in industrial production, Asia, the "green" movement and financial services. Those are the messages from March's top-performing exchange traded funds, used by investors as trading tools to bet on entire industries or regions. Assuming the stock-market turnaround in early March was more than an ephemeral bounce in a continuing bear market, lessons can be gleaned from the makeup of the adjoining list of the 25 best non-leveraged ETF performers for the month. Lesson 1: Industrial production will pick up. Six metals ETFs are among the best performers, suggesting companies are ramping up manufacturing. Because basic metals are usually several levels below final product consumption, the strength of this sector indicates confidence in a broad recovery for manufacturing. However, one of the metals plays is ELEMENTS MLCX Gold ( GOE), with the interest in gold reflecting concern about inflation. With 24% of its portfolio in metals and mining, PowerShares FTSE RAFI Basic Materials Sector Portfolio ( PRFM) was included with the metals. Its primary holdings of chemicals also play a crucial raw-material role in basic industry. Lesson 2: The Asia-Pacific region could lead the worldwide recovery. The top-performing non-leveraged ETF in March -- iShares MSCI South Korea ( EWY) -- vaulted 31%, followed closely by WisdomTree Pacific ex-Japan High-Yielding Equity Fund ( DNH), which climbed 24%. There are three other Asia-Pacific ETFs on the list. Lesson 3: "Green" investments are for real. Even those who don't agree with the science behind global warming can't ignore the facts that the second- and fourth-best performers are solar investments, and No. 10, the iPath Barclays Capital Global Carbon Index Total Return ( GRN), is a "carbon emissions" play. Commitments by Congress and the Obama administration to support and subsidize these industries are largely responsible for their attractiveness to investors.