Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 326 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
2. 2.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is (d) the ironing time
4. 4.True or false: cutting the lemon is a job for an adult. (a) False (b) True
5. 5.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
6. 6.True or false: cutting the lemon is a job a child can do. (a) False (b) True
7. 7.True or false: writing the message is a job a child can do. (a) False (b) True
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) turmeric powder (d) a cotton bud
9. 9.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) a rainbow (d) blue words
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
11. 11.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) reading the message
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the kind of juice (d) the same cotton bud
13. 13.True or false: white paper is needed for the secret lemon message. (a) True (b) False
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
15. 15.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
16. 16.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the paper ate it (d) the ink is magnetic
17. 17.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
18. 18.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) ironing the paper (c) reading the message (d) letting the paper dry
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) how dark the writing is (c) the kind of juice
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a mirror (c) a magnet (d) a battery cell
21. 21.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
22. 22.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) putting the iron away
23. 23.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) lemon juice (c) a small bowl (d) an adult with an iron
25. 25.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) brown (d) blue
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) lemon juice (d) a battery cell
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a small bowl (d) white paper
29. 29.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) an adult with an iron (d) a magnet
32. 32.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
33. 33.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) white paper (c) a cotton bud (d) a small bowl
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
36. 36.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) a small bowl (d) an adult with an iron
38. 38.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) ironing the paper (d) putting the iron away
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) yeast (d) a small bowl

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