Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 41 · 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.🧺 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) a balloon (d) a cotton bud
2. 2.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) cutting the lemon (c) letting the paper dry (d) writing the message
3. 3.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) reading the message (d) ironing the paper
4. 4.True or false: cutting the lemon is a job for an adult. (a) False (b) True
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) an adult with an iron (c) lemon juice (d) a small bowl
7. 7.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
8. 8.🛟 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
9. 9.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the iron setting (c) the same paper (d) the same cotton bud
11. 11.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) white (d) green
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) a cotton bud (d) white paper
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
14. 14.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) plugging in the iron (d) putting the iron away
15. 15.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
16. 16.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) the youngest child (d) any child
17. 17.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) yes, if shaken (d) no, it stays brown
18. 18.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) writing the message (d) reading the message
19. 19.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) a balloon (d) a magnet
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
21. 21.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) a mirror (d) a small bowl
23. 23.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
24. 24.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
25. 25.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) a rainbow (d) dark brown words
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a mirror (c) an adult with an iron (d) a cotton bud
27. 27.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) dipping the cotton bud
28. 28.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) musical (d) physical
29. 29.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
30. 30.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) reading the message (d) writing the message
31. 31.⚖️ 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 keep it the same (c) we measure it
32. 32.True or false: plugging in the iron is a job a child can do. (a) True (b) False
33. 33.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) letting the paper dry (d) plugging in the iron
34. 34.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) writing stays faint (d) the paper floats
35. 35.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) cutting the lemon (d) writing the message
36. 36.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
37. 37.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) a cotton bud (c) lemon juice (d) an adult with an iron
39. 39.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) an adult with an iron (d) turmeric powder
40. 40.⚖️ 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 same paper (c) the kind of juice (d) the ironing time

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