Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 151 · 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) a cotton bud (b) white paper (c) a small bowl (d) a magnet
2. 2.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
3. 3.True or false: yeast is needed for the secret lemon message. (a) False (b) True
4. 4.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
5. 5.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
7. 7.⚖️ 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
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) white paper (d) a magnet
9. 9.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
10. 10.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) reading the message
11. 11.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the same cotton bud (c) how dark the writing is (d) the kind of juice
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
14. 14.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) yeast (c) a mirror (d) a balloon
16. 16.🔍 Which is the odd one out? (a) cutting the lemon (b) dipping the cotton bud (c) letting the paper dry (d) reading the message
17. 17.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) cutting the lemon (d) plugging in the iron
18. 18.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
19. 19.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) ironing the paper (d) putting the iron away
20. 20.True or false: plugging in the iron is a job a child can do. (a) True (b) False
21. 21.True or false: white paper is needed for the secret lemon message. (a) False (b) True
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
23. 23.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it can burn skin (d) it is magnetic
24. 24.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) writing turns green (d) it gets darker
25. 25.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
26. 26.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) magnetic (d) chemical
27. 27.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
28. 28.⚖️ 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
29. 29.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a cotton bud (d) a mirror
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the ironing time (c) the kind of juice
31. 31.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) heat adds colour (c) paper turns lemony (d) the iron is brown
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) lemon juice (c) a small bowl (d) a cotton bud
34. 34.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) green (d) blue
35. 35.⚖️ 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
36. 36.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) cutting the lemon (d) writing the message
37. 37.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) a rainbow (d) dark brown words
38. 38.True or false: putting the iron away is a job a child can do. (a) True (b) False
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a balloon (d) an adult with an iron
40. 40.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) writing the message

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