diff --git a/.vscode/extensions.json b/.vscode/extensions.json
new file mode 100644
index 0000000..60084df
--- /dev/null
+++ b/.vscode/extensions.json
@@ -0,0 +1,6 @@
+{
+    "recommendations": [
+        "formulahendry.dotnet-test-explorer",
+        "ms-dotnettools.csharp"
+    ]
+}
\ No newline at end of file
diff --git a/.vscode/launch.json b/.vscode/launch.json
new file mode 100644
index 0000000..bac62d0
--- /dev/null
+++ b/.vscode/launch.json
@@ -0,0 +1,26 @@
+{
+    "version": "0.2.0",
+    "configurations": [
+        {
+            // Use IntelliSense to find out which attributes exist for C# debugging
+            // Use hover for the description of the existing attributes
+            // For further information visit https://github.com/OmniSharp/omnisharp-vscode/blob/master/debugger-launchjson.md
+            "name": ".NET Core Launch (console)",
+            "type": "coreclr",
+            "request": "launch",
+            "preLaunchTask": "build",
+            // If you have changed target frameworks, make sure to update the program path.
+            "program": "${workspaceFolder}/Koans/bin/Debug/net5.0/Koans.dll",
+            "args": [],
+            "cwd": "${workspaceFolder}/Koans",
+            // For more information about the 'console' field, see https://aka.ms/VSCode-CS-LaunchJson-Console
+            "console": "internalConsole",
+            "stopAtEntry": false
+        },
+        {
+            "name": ".NET Core Attach",
+            "type": "coreclr",
+            "request": "attach"
+        }
+    ]
+}
\ No newline at end of file
diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..06b5767
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,5 @@
+{
+    "dotnet-test-explorer.testProjectPath": "Koans/Koans.csproj",
+    "dotnet-test-explorer.runInParallel": true,
+    "dotnet-test-explorer.autoWatch": true
+}
\ No newline at end of file
diff --git a/.vscode/tasks.json b/.vscode/tasks.json
new file mode 100644
index 0000000..5bdd109
--- /dev/null
+++ b/.vscode/tasks.json
@@ -0,0 +1,42 @@
+{
+    "version": "2.0.0",
+    "tasks": [
+        {
+            "label": "build",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "build",
+                "${workspaceFolder}/Koans/Koans.csproj",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        },
+        {
+            "label": "publish",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "publish",
+                "${workspaceFolder}/Koans/Koans.csproj",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        },
+        {
+            "label": "watch",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "watch",
+                "run",
+                "${workspaceFolder}/Koans/Koans.csproj",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        }
+    ]
+}
\ No newline at end of file
diff --git a/Koans/Koans.csproj b/Koans/Koans.csproj
index 62967c3..362ae50 100644
--- a/Koans/Koans.csproj
+++ b/Koans/Koans.csproj
@@ -1,132 +1,18 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <PropertyGroup>
-    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
-    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
-    <ProjectGuid>{9913EE45-EB7F-4C31-B62F-D5172DE47C51}</ProjectGuid>
-    <OutputType>Library</OutputType>
-    <AppDesignerFolder>Properties</AppDesignerFolder>
-    <RootNamespace>Koans</RootNamespace>
-    <AssemblyName>Koans</AssemblyName>
-    <TargetFrameworkVersion>v4.6.1</TargetFrameworkVersion>
-    <FileAlignment>512</FileAlignment>
-    <ProjectTypeGuids>{3AC096D0-A1C2-E12C-1390-A8335801FDAB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
-    <VisualStudioVersion Condition="'$(VisualStudioVersion)' == ''">10.0</VisualStudioVersion>
-    <VSToolsPath Condition="'$(VSToolsPath)' == ''">$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)</VSToolsPath>
-    <ReferencePath>$(ProgramFiles)\Common Files\microsoft shared\VSTT\$(VisualStudioVersion)\UITestExtensionPackages</ReferencePath>
-    <IsCodedUITest>False</IsCodedUITest>
-    <TestProjectType>UnitTest</TestProjectType>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
-    <DebugSymbols>true</DebugSymbols>
-    <DebugType>full</DebugType>
-    <Optimize>false</Optimize>
-    <OutputPath>bin\Debug\</OutputPath>
-    <DefineConstants>DEBUG;TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-    <RunCodeAnalysis>true</RunCodeAnalysis>
-    <Prefer32Bit>false</Prefer32Bit>
-    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
-    <DebugType>pdbonly</DebugType>
-    <Optimize>true</Optimize>
-    <OutputPath>bin\Release\</OutputPath>
-    <DefineConstants>TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-    <Prefer32Bit>false</Prefer32Bit>
-    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
-    <RunCodeAnalysis>true</RunCodeAnalysis>
-  </PropertyGroup>
-  <ItemGroup>
-    <Reference Include="System" />
-    <Reference Include="System.Core" />
-    <Reference Include="System.Drawing" />
-    <Reference Include="System.Reactive.Core, Version=2.2.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
-      <HintPath>..\packages\Rx-Core.2.2.5\lib\net45\System.Reactive.Core.dll</HintPath>
-      <Private>True</Private>
-    </Reference>
-    <Reference Include="System.Reactive.Interfaces, Version=2.2.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
-      <HintPath>..\packages\Rx-Interfaces.2.2.5\lib\net45\System.Reactive.Interfaces.dll</HintPath>
-      <Private>True</Private>
-    </Reference>
-    <Reference Include="System.Reactive.Linq, Version=2.2.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
-      <HintPath>..\packages\Rx-Linq.2.2.5\lib\net45\System.Reactive.Linq.dll</HintPath>
-      <Private>True</Private>
-    </Reference>
-    <Reference Include="System.Reactive.PlatformServices, Version=2.2.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
-      <HintPath>..\packages\Rx-PlatformServices.2.2.5\lib\net45\System.Reactive.PlatformServices.dll</HintPath>
-      <Private>True</Private>
-    </Reference>
-    <Reference Include="Microsoft.CSharp" />
-  </ItemGroup>
-  <Choose>
-    <When Condition="('$(VisualStudioVersion)' == '10.0' or '$(VisualStudioVersion)' == '') and '$(TargetFrameworkVersion)' == 'v3.5'">
-      <ItemGroup>
-        <Reference Include="Microsoft.VisualStudio.QualityTools.UnitTestFramework, Version=10.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" />
-      </ItemGroup>
-    </When>
-    <Otherwise>
-      <ItemGroup>
-        <Reference Include="Microsoft.VisualStudio.QualityTools.UnitTestFramework" />
-      </ItemGroup>
-    </Otherwise>
-  </Choose>
-  <Choose>
-    <When Condition="'$(VisualStudioVersion)' == '10.0' And '$(IsCodedUITest)' == 'True'">
-      <ItemGroup>
-        <Reference Include="Microsoft.VisualStudio.QualityTools.CodedUITestFramework, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-          <Private>False</Private>
-        </Reference>
-        <Reference Include="Microsoft.VisualStudio.TestTools.UITest.Common, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-          <Private>False</Private>
-        </Reference>
-        <Reference Include="Microsoft.VisualStudio.TestTools.UITest.Extension, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-          <Private>False</Private>
-        </Reference>
-        <Reference Include="Microsoft.VisualStudio.TestTools.UITesting, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-          <Private>False</Private>
-        </Reference>
-      </ItemGroup>
-    </When>
-  </Choose>
-  <ItemGroup>
-    <Compile Include="Lessons\Lesson0Lambdas.cs" />
-    <Compile Include="Lessons\WriteYourOwnLesson.cs" />
-    <Compile Include="Lessons\Lesson3Linq.cs" />
-    <Compile Include="Lessons\Lesson7AsyncInvoke.cs" />
-    <Compile Include="Lessons\Lesson1ObservableStreams.cs" />
-    <Compile Include="Lessons\Lesson5Events.cs" />
-    <Compile Include="Lessons\Lesson2ComposableObservations.cs" />
-    <Compile Include="Lessons\Lesson4Time.cs" />
-    <Compile Include="Lessons\Lesson6AdvancedStreams.cs" />
-    <Compile Include="Tests\Lesson0LambdasTest.cs" />
-    <Compile Include="Tests\Lesson7AsyncInvokeTest.cs" />
-    <Compile Include="Tests\Lesson6AdvancedStreamsTest.cs" />
-    <Compile Include="Tests\Lesson5EventsTest.cs" />
-    <Compile Include="Utils\Range.cs" />
-    <Compile Include="Utils\RxKoans.cs" />
-    <Compile Include="Utils\StringUtils.cs" />
-    <Compile Include="Properties\AssemblyInfo.cs" />
-    <Compile Include="Tests\Lesson4TimeTest.cs" />
-    <Compile Include="Tests\Lesson2ComposibleTest.cs" />
-    <Compile Include="Tests\Lesson1ObservableStreamsTest.cs" />
-    <Compile Include="Utils\KoanUtils.cs" />
-    <Compile Include="Tests\Lesson3LinqTest.cs" />
-    <Compile Include="Utils\ThreadUtils.cs" />
-  </ItemGroup>
-  <ItemGroup>
-    <None Include="packages.config" />
-  </ItemGroup>
-  <Import Project="$(VSToolsPath)\TeamTest\Microsoft.TestTools.targets" Condition="Exists('$(VSToolsPath)\TeamTest\Microsoft.TestTools.targets')" />
-  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
-  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
-       Other similar extension points exist, see Microsoft.Common.targets.
-  <Target Name="BeforeBuild">
-  </Target>
-  <Target Name="AfterBuild">
-  </Target>
-  -->
+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<TargetFramework>net5.0</TargetFramework>
+		<GenerateTargetFrameworkAttribute>false</GenerateTargetFrameworkAttribute>
+		<GenerateAssemblyInfo>false</GenerateAssemblyInfo>
+		<IsPackable>false</IsPackable>
+	</PropertyGroup>
+
+	<ItemGroup>
+		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.9.4" />
+		<PackageReference Include="MSTest.TestAdapter" Version="2.2.3" />
+		<PackageReference Include="MSTest.TestFramework" Version="2.2.3" />
+		<PackageReference Include="coverlet.collector" Version="3.0.2" />
+		<PackageReference Include="System.Reactive.Linq" Version="5.0.0" />
+	</ItemGroup>
+
 </Project>
\ No newline at end of file
diff --git a/Koans/Lessons/Lesson1ObservableStreams.cs b/Koans/Lessons/Lesson1ObservableStreams.cs
index 93924d1..6e6a77e 100644
--- a/Koans/Lessons/Lesson1ObservableStreams.cs
+++ b/Koans/Lessons/Lesson1ObservableStreams.cs
@@ -7,6 +7,7 @@
 using System.Threading;
 using Koans.Utils;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Range = Koans.Utils.Range;
 
 namespace Koans.Lessons
 {
diff --git a/Koans/Lessons/Lesson2ComposableObservations.cs b/Koans/Lessons/Lesson2ComposableObservations.cs
index 5ae7635..be41c43 100644
--- a/Koans/Lessons/Lesson2ComposableObservations.cs
+++ b/Koans/Lessons/Lesson2ComposableObservations.cs
@@ -3,6 +3,7 @@
 using Koans.Utils;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using System;
+using Range = Koans.Utils.Range;
 
 namespace Koans.Lessons
 {
diff --git a/Rx.NETKoans.sln b/Rx.NETKoans.sln
index fbe790e..b300740 100644
--- a/Rx.NETKoans.sln
+++ b/Rx.NETKoans.sln
@@ -1,9 +1,9 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
-# Visual Studio 14
-VisualStudioVersion = 14.0.25123.0
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.31402.337
 MinimumVisualStudioVersion = 10.0.40219.1
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Koans", "Koans\Koans.csproj", "{9913EE45-EB7F-4C31-B62F-D5172DE47C51}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Koans", "Koans\Koans.csproj", "{E710D53A-28FB-4DD6-9FA3-8D2C5411ADC5}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -11,12 +11,15 @@ Global
 		Release|Any CPU = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{9913EE45-EB7F-4C31-B62F-D5172DE47C51}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{9913EE45-EB7F-4C31-B62F-D5172DE47C51}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{9913EE45-EB7F-4C31-B62F-D5172DE47C51}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{9913EE45-EB7F-4C31-B62F-D5172DE47C51}.Release|Any CPU.Build.0 = Release|Any CPU
+		{E710D53A-28FB-4DD6-9FA3-8D2C5411ADC5}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{E710D53A-28FB-4DD6-9FA3-8D2C5411ADC5}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{E710D53A-28FB-4DD6-9FA3-8D2C5411ADC5}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{E710D53A-28FB-4DD6-9FA3-8D2C5411ADC5}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
 	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {938DEC59-C441-4D5B-A181-A3E79ADFADFA}
+	EndGlobalSection
 EndGlobal