Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 714 · 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: letting the paper dry is a job for an adult. (a) True (b) False
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) yeast (d) an adult with an iron
3. 3.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
4. 4.🛟 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
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is (d) the ironing time
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) lemon juice (d) white paper
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a battery cell (d) lemon juice
8. 8.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
9. 9.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) putting the iron away (d) writing the message
10. 10.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
11. 11.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) reading the message (c) plugging in the iron (d) ironing the paper
12. 12.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
13. 13.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) musical (d) physical
14. 14.True or false: white paper is needed for the secret lemon message. (a) True (b) False
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a magnet (d) an adult with an iron
16. 16.🍋 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
17. 17.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) white (d) blue
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) yeast (d) white paper
19. 19.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
20. 20.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if shaken (d) yes, if cooled
21. 21.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) ironing the paper
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a cotton bud (d) a battery cell
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
24. 24.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
26. 26.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a magnet (d) a small bowl
27. 27.True or false: cutting the lemon is a job a child can do. (a) True (b) False
28. 28.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
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 measure it (b) we keep it the same (c) we change it
30. 30.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) the youngest child (d) only an adult
31. 31.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) cutting the lemon (d) letting the paper dry
32. 32.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
33. 33.⚖️ 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 cotton bud (d) the ironing time
34. 34.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
35. 35.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a balloon (c) a battery cell (d) turmeric powder
36. 36.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
39. 39.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) paper turns lemony (d) the juice scorches first
40. 40.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False

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