Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 736 · 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.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) cutting the lemon (d) letting the paper dry
2. 2.🍋 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
3. 3.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) yeast (d) a cotton bud
5. 5.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a battery cell (d) an adult with an iron
7. 7.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) reading the message (c) letting the paper dry (d) dipping the cotton bud
8. 8.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) a balloon (d) a mirror
9. 9.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a mirror (c) white paper (d) a small bowl
11. 11.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) rub your eyes (d) skip washing
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
13. 13.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the same cotton bud (c) the kind of juice (d) how dark the writing is
15. 15.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) ironing the paper (d) plugging in the iron
16. 16.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
19. 19.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same paper
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a balloon (c) a cotton bud (d) lemon juice
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
23. 23.True or false: cutting the lemon is a job a child can do. (a) True (b) False
24. 24.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
25. 25.True or false: ironing the paper is a job for an adult. (a) True (b) False
26. 26.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) a mirror (d) a balloon
28. 28.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) ironing the paper (d) reading the message
29. 29.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) plugging in the iron (d) dipping the cotton bud
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) white paper (d) a mirror
31. 31.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) yes, if shaken (d) no, it stays brown
32. 32.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
33. 33.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
34. 34.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) blue words (d) a rainbow
35. 35.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
36. 36.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) the iron is brown (c) heat adds colour (d) paper turns lemony
37. 37.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) brown (d) green
38. 38.⚖️ 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
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) lemon juice (d) a battery cell
40. 40.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) putting the iron away (d) writing the message

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