Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 491 · 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) white paper (b) lemon juice (c) a magnet (d) an adult with an iron
2. 2.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
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 iron setting (c) the kind of juice (d) the same paper
4. 4.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) letting the paper dry
5. 5.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
6. 6.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
8. 8.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) dipping the cotton bud (d) cutting the lemon
9. 9.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
10. 10.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
11. 11.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
12. 12.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) reading the message (d) cutting the lemon
13. 13.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) a mirror (d) a magnet
14. 14.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
15. 15.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) ironing the paper (d) putting the iron away
16. 16.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) the juice scorches first (d) paper turns lemony
17. 17.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) blue (d) brown
18. 18.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
19. 19.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a battery cell (d) an adult with an iron
21. 21.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a mirror (c) a battery cell (d) turmeric powder
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) white paper (d) yeast
24. 24.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is magnetic (c) it is sticky (d) it is cold
25. 25.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
26. 26.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a mirror (c) a magnet (d) a balloon
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a cotton bud (d) a magnet
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
30. 30.True or false: yeast is needed for the secret lemon message. (a) True (b) False
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a small bowl (c) lemon juice (d) white paper
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
34. 34.⚖️ 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
35. 35.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) ironing the paper (d) writing the message
36. 36.🔮 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
37. 37.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
38. 38.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
39. 39.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) a cotton bud (d) a battery cell

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