Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 822 · 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 is not needed for the secret lemon message? (a) a balloon (b) lemon juice (c) a cotton bud (d) a small bowl
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
3. 3.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) turmeric powder (d) a cotton bud
5. 5.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it can burn skin (d) it is magnetic
6. 6.🔮 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
7. 7.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) yeast (d) lemon juice
8. 8.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
9. 9.⚖️ 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
10. 10.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) the paper floats (d) writing stays faint
11. 11.⚖️ 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 keep it the same (c) we measure it
12. 12.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
13. 13.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
14. 14.True or false: cutting the lemon is a job a child can do. (a) False (b) True
15. 15.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) turmeric powder (d) a cotton bud
17. 17.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) any child (d) only an adult
18. 18.⚖️ 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 kind of juice (c) how dark the writing is (d) the same paper
19. 19.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) cutting the lemon (d) reading the message
20. 20.🍋 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
21. 21.True or false: letting the paper dry is a job for an adult. (a) False (b) True
22. 22.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) brown (d) white
23. 23.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) skip washing (d) lick your fingers
24. 24.⚖️ 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
25. 25.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
27. 27.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
28. 28.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
29. 29.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) lemon juice (d) yeast
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
32. 32.⚖️ 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
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is (d) the ironing time
34. 34.🧺 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
35. 35.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
36. 36.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) plugging in the iron (c) letting the paper dry (d) writing the message
37. 37.🍋 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
38. 38.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) letting the paper dry
39. 39.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
40. 40.True or false: white paper is needed for the secret lemon message. (a) True (b) False

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