Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 683 · 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 is the odd one out? (a) writing the message (b) putting the iron away (c) plugging in the iron (d) cutting the lemon
2. 2.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) putting the iron away (d) letting the paper dry
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a small bowl (d) a balloon
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the ironing time (c) the same paper (d) the kind of juice
5. 5.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it can burn skin (d) it is sticky
6. 6.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
7. 7.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) a cotton bud (c) a small bowl (d) lemon juice
9. 9.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
11. 11.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
12. 12.⚖️ 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
13. 13.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
14. 14.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) dipping the cotton bud (c) writing the message (d) letting the paper dry
15. 15.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
16. 16.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) the paper floats (d) writing turns green
17. 17.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) ironing the paper (d) putting the iron away
18. 18.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
19. 19.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, in the dark (d) yes, if cooled
20. 20.🛟 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
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) lemon juice (d) an adult with an iron
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) white paper (d) a mirror
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) lemon juice (d) an adult with an iron
24. 24.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
25. 25.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) a rainbow (d) blue words
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) lemon juice (d) a battery cell
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) turmeric powder (d) an adult with an iron
28. 28.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) blue (d) brown
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a small bowl (d) yeast
30. 30.True or false: letting the paper dry is a job a child can do. (a) True (b) False
31. 31.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a small bowl (c) turmeric powder (d) a magnet
32. 32.⚖️ 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
33. 33.True or false: writing the message is a job for an adult. (a) True (b) False
34. 34.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
35. 35.True or false: cutting the lemon is a job for an adult. (a) True (b) False
36. 36.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
38. 38.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
39. 39.⚖️ 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
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False

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